I just got a used makerbot 2. Its my 4th printer but first makerbot. It has an issue where it extrudes fine when loading filament etc. It prints an absolutely perfect raft. But then in the first few layers of the actual part it stops extruding. When i pull the filament out i see the divot where the extruder teeth ground into the filament. So i went through all the unclogging procedures including running a .3mm wire through the nozzle. Im certain there is no partial clog. I tried 3 different filaments including some brand new makerbot filament i bought today. It also appears that if you physically hold the filament it continues to print. I took apart the extruder assembly completely and cleaned it up. Everything looks in good order and it has the upgraded spring extruder as well. Does anyone have any ideas?

Thanks,
Zach