As a separate issue, I'm having trouble ever since I swapped the original motor for the newer/faster one. In swapping the motors, the washers were crushed, so I switched to the 3/32" pin that Elmoret sent (thanks!). Unfortunately, the pins didn't work for long. I noticed that the motor axles for the two motors are different - the "flat" on the old motor is much larger than the "flat" on the new motor, which is very nearly round. I also noticed that the pins are quite loose between the motor axle and the square end of the hex socket. Perhaps because of this, the pins didn't work with the new motor - after making it around one or two times, they basically rolled around the motor axle and wore down.
Tomorrow's trip to the hardware store I think I'll try one size larger (1/8") to see if that fits more tightly.
I suspect that the underlying issue is a blockage, and hopefully I can get the nozzle off and clear that out. Because "let it soak up heat, then push it through" isn't working.