Kenwood Chef A 901 bang and smoke?

I use my Kenwood Chef A 901 Serial # 0840909 for mixing boilies which is quite a heavy job I presume
It is 50Hz 1/3 hp
I was near the end of a mix today and just getting the dough to final consistancy and there was a bang and electric smelling smoke came out of the motor area
The mixer kept running and I stopped it immediately
After the smoke had cleared and it had rested for a bit I tried it without load and was still working
Any ideas on what it may have been and what I will need to do to make it good and safe again??
I am no expert in anything like this
Thanks in advance