diff --git a/src/main/java/cr0s/warpdrive/block/collection/TileEntityLaserTreeFarm.java b/src/main/java/cr0s/warpdrive/block/collection/TileEntityLaserTreeFarm.java
index 50c5ec3f..f4cf7955 100644
--- a/src/main/java/cr0s/warpdrive/block/collection/TileEntityLaserTreeFarm.java
+++ b/src/main/java/cr0s/warpdrive/block/collection/TileEntityLaserTreeFarm.java
@@ -139,11 +139,30 @@ public class TileEntityLaserTreeFarm extends TileEntityAbstractMiner {
 				return;
 			}
 		} else if (currentState == STATE_SCAN) {
-			int energyCost = TREE_FARM_ENERGY_PER_SURFACE * (1 + 2 * radiusX) * (1 + 2 * radiusZ);
+			final int energyCost = TREE_FARM_ENERGY_PER_SURFACE * (1 + 2 * radiusX) * (1 + 2 * radiusZ);
 			if (delayTicks == 1) {
 				if (WarpDriveConfig.LOGGING_COLLECTION) {
 					WarpDrive.logger.debug("Scan pre-tick");
 				}
+				
+				// validate environment: clearance above
+				final Block blockAbove = worldObj.getBlock(xCoord, yCoord + 1, zCoord);
+				if ( !isLog(blockAbove)
+				  && !isLeaf(blockAbove)
+				  && !blockAbove.isAir(worldObj, xCoord, yCoord + 1, zCoord) ) {
+					PacketHandler.sendSpawnParticlePacket(worldObj, "jammed", (byte) 5, new Vector3(this).translate(0.5F),
+					                                      new Vector3(0.0D, 0.0D, 0.0D),
+					                                      1.0F, 1.0F, 1.0F,
+					                                      1.0F, 1.0F, 1.0F,
+					                                      32);
+					
+					currentState = STATE_WARMUP;	// going back to warmup state to show the animation when it'll be back online
+					delayTicks = 0;
+					delayTargetTicks = TREE_FARM_LOW_POWER_DELAY_TICKS;
+					updateMetadata(BlockLaserTreeFarm.ICON_SCANNING_LOW_POWER);
+					return;
+				}
+				
 				// check power level
 				enoughPower = consumeEnergyFromLaserMediums(energyCost, true);
 				if (!enoughPower) {
@@ -254,7 +273,7 @@ public class TileEntityLaserTreeFarm extends TileEntityAbstractMiner {
 							}
 							
 							// consume power
-							int energyCost = TREE_FARM_ENERGY_PER_WET_SPOT;
+							final int energyCost = TREE_FARM_ENERGY_PER_WET_SPOT;
 							enoughPower = consumeEnergyFromLaserMediums(energyCost, false);
 							if (!enoughPower) {
 								delayTargetTicks = TREE_FARM_LOW_POWER_DELAY_TICKS;
@@ -415,8 +434,8 @@ public class TileEntityLaserTreeFarm extends TileEntityAbstractMiner {
 				}
 				
 				// consume power
-				double energyCost = TREE_FARM_ENERGY_PER_SAPLING;
-				enoughPower = consumeEnergyFromLaserMediums((int) Math.round(energyCost), false);
+				final int energyCost = TREE_FARM_ENERGY_PER_SAPLING;
+				enoughPower = consumeEnergyFromLaserMediums(energyCost, false);
 				if (!enoughPower) {
 					delayTargetTicks = TREE_FARM_LOW_POWER_DELAY_TICKS;
 					updateMetadata(BlockLaserTreeFarm.ICON_PLANTING_LOW_POWER);
diff --git a/src/main/java/cr0s/warpdrive/network/MessageSpawnParticle.java b/src/main/java/cr0s/warpdrive/network/MessageSpawnParticle.java
index 8a5a37d9..43b4c5bc 100644
--- a/src/main/java/cr0s/warpdrive/network/MessageSpawnParticle.java
+++ b/src/main/java/cr0s/warpdrive/network/MessageSpawnParticle.java
@@ -1,5 +1,6 @@
 package cr0s.warpdrive.network;
 
+import cr0s.warpdrive.Commons;
 import cr0s.warpdrive.WarpDrive;
 import cr0s.warpdrive.config.WarpDriveConfig;
 import cr0s.warpdrive.data.Vector3;
@@ -14,6 +15,7 @@ import net.minecraft.client.particle.EntityExplodeFX;
 import net.minecraft.client.particle.EntityFX;
 import net.minecraft.client.particle.EntityFireworkSparkFX;
 import net.minecraft.client.particle.EntityFlameFX;
+import net.minecraft.client.particle.EntityHeartFX;
 import net.minecraft.client.particle.EntitySnowShovelFX;
 import net.minecraft.client.particle.EntitySpellParticleFX;
 import net.minecraft.init.Items;
@@ -25,6 +27,7 @@ import cpw.mods.fml.common.network.simpleimpl.IMessageHandler;
 import cpw.mods.fml.common.network.simpleimpl.MessageContext;
 import cpw.mods.fml.relauncher.Side;
 import cpw.mods.fml.relauncher.SideOnly;
+import net.minecraftforge.common.util.ForgeDirection;
 
 public class MessageSpawnParticle implements IMessage, IMessageHandler<MessageSpawnParticle, IMessage> {
 	
@@ -115,7 +118,7 @@ public class MessageSpawnParticle implements IMessage, IMessageHandler<MessageSp
 		// adjust color as needed
 		EntityFX effect;
 		double noiseLevel = direction.getMagnitude() * 0.35D;
-		for (int i = 0; i < quantity; i++) {
+		for (int index = 0; index < quantity; index++) {
 			Vector3 directionRandomized = new Vector3(
 					direction.x + noiseLevel * (world.rand.nextFloat() - world.rand.nextFloat()),
 					direction.y + noiseLevel * (world.rand.nextFloat() - world.rand.nextFloat()),
@@ -153,6 +156,27 @@ public class MessageSpawnParticle implements IMessage, IMessageHandler<MessageSp
 			case "cloud":
 				effect = new EntityCloudFX(world, origin.x, origin.y, origin.z, directionRandomized.x, directionRandomized.y, directionRandomized.z);
 				break;
+			
+			case "jammed":// jammed machine particle reusing vanilla angryVillager particle
+				// as of MC1.7.10, direction vector is ignored by upstream
+				final ForgeDirection directionFacing = Commons.getHorizontalDirectionFromEntity(Minecraft.getMinecraft().thePlayer);
+				if (directionFacing.offsetX != 0) {
+					effect = new EntityHeartFX(world,
+					                           origin.x + 0.51D * directionFacing.offsetX,
+					                           origin.y - 0.50D + world.rand.nextDouble(),
+					                           origin.z - 0.50D + world.rand.nextDouble(),
+					                           directionRandomized.x, directionRandomized.y, directionRandomized.z,
+					                           0.5F + world.rand.nextFloat() * 1.5F);
+				} else {
+					effect = new EntityHeartFX(world,
+					                           origin.x - 0.50D + world.rand.nextDouble(),
+					                           origin.y - 0.50D + world.rand.nextDouble(),
+					                           origin.z + 0.51D * directionFacing.offsetZ,
+					                           directionRandomized.x, directionRandomized.y, directionRandomized.z,
+					                           0.5F + world.rand.nextFloat() * 1.5F);
+				}
+				effect.setParticleTextureIndex(81);
+				break;
 			} 
 			if (baseRed >= 0.0F && baseGreen >= 0.0F && baseBlue >= 0.0F) {
 				effect.setRBGColorF(baseRed, baseGreen, baseBlue);