P.M. D.C. Motor for Treadmill

Hi I am working on an Image 15.0 R Treadmill. As soon as you start it , it shuts down as if the circuit has been interrupted. I unhooked the drive belt so that there was no resistance to it and it does the same still. The speed sensor seems to be working okay so I pulled the controller (board) and tried re-flowing it. as I flip the treadmills switch on not starting the treadmill-just turning the power on the motor runs for about 3 seconds. Because the cover is off while I am working on it I can see that during that 3 second window the motor has a spark (bolt) from one of the bolts to the post (I think stater) the one that if the motor were disassembled the part spinning inside the copper wind. I don't remember what it's called (armature?) Anyway this arching does not re-occur unless I completely unhook the board once more and re-assemble. After re-flow the motor still just begins to load (start) bumps about 1/2 a rotation and stops. I read an article here that Iceng had commented about bringing his P.M. D.C. Motor model # c335483304 back to life......it is the exact motor....my girlfriend has been on me about fixing her treadmill so here I am. Anything would be of great interest and help to me. Thanks a million in advance. Troy

Sounds like the motor may have a bad coil. Have you tested the motor with a meter to see if the coils all measure the same?