What do you mean by acting up? Getting louder and kinda grinding noise?
Or shutting down? If the combustion plate (where the coal burns) gets clogged with ash, it will not perform optimally. You should clean under the burn plate really well at the year end maintenance of the stove.
Have you oiled the motor ? There are 2 small holes for the bearing, use some good small motor oil (3 in 1, etc).
I noticed ours is getting a bit louder, but works fine. (2nd season running) It runs 24/7 from Nov-Mar (Approx). Except for a few times shutting down to vacuum things out. May have to replace next year?
I believe it is a DAYTON blower,Model #7021-3466
#4C440 60CFM 3030RPM 115volts 60/50hz
old # 1C180
Check here. http://www.electricmotorwarehouse.com/dayton_blower.htm