Here is a link for the hot end assembly process.
Please make sure to contact email@example.com, if the tool head is still under warranty.(which it may not be after removing the nozzle)
If not, you should be able to tell where the filament is jammed, by how high up the hot end the plunger that you are using goes. This will tell you where the clog is. Many times the clog will be in the tube that feeds down to the hot end and it can’t be cleared because you can’t get the tube(where the filament is stuck) as hot as the hot end. I have had individuals tell me that they drill out the filament so that they can save the hot end. You can purchase another hot end for $70.00 and that will solve all of the problems.
The link will show you where the set screw is and how to disassemble the hot end from the feed tube. When you have to put it back together, they are using a nylon tape, but Lulzbot uses a thread locker.
Extreme-Temperature Pipe Sealant & Threadlocker, 4 oz bottle, blue Mcmaster 7604A55(sku)
You will want to be careful with filaments like wood fill as they are a PLA based filament most of the time and they will crystallize above 240C.
I hope this will help, but you may just need to get another hot end.