Had a similar problem some years back with a different machine. Whatever it was set for, the thing seemed to want to spin and to do so at full chat. Turned out to be ridiculously simple: the speed sensor target on the motor shaft had fallen off and the machine thought it wasn't running so wound itself up as far as it could. (I found the bit on the floor underneath the machine, screwed it back in with a bit of hreadlock and all was well).
Looks like it may be a similar issue. Could bew worth exploring the machine and seeing how it senses motor speed.
XX
August 2015
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