Hi everyone,

The extruder cooling fan on my Replicator 2 completely stopped spinning recently. In an attempt to fix it, I ordered an identical replacement fan from MakerBot and soldered it in place of the old one. The fan spun when it was supposed to (i.e. any time the extruder was heated past 50 degrees Celsius), but it only spun very slowly/weakly, even as the extruder heated to the full 230 degrees. I tested it with a multimeter and found that the fan was receiving far less than 24V (I couldn't get a solid read on how much voltage it *was* receiving, but the readings peaked in the low single digits). After a few small test prints, the fan again stopped working entirely, and no longer spins at any time.

According to Google consensus, the most likely cause of this problem is a blown MOSFET on the motherboard. However, the closest problems to mine that I've seen don't mention anything about the fan spinning slowly first. Is a blown MOSFET capable of weakening a fan instead of stopping it outright? Are there any alternate possibilities besides the motherboard that I could check out before I pay $100 to get the motherboard replaced? I know it's not the EEPROM because, when the fan was spinning weakly, it correctly started to turn on at 50 degrees, and I know it's not overtightening of the bolts because the fan was still spinning just as weakly when it was outside of the extruder assembly.

Thank you!