Google Clarkson Company. I have had 6 or 7 motors rebuilt from Steve Clarkson and he is the only certified SEM distributor in the USA. He will diagnose it and quote you with the price, after he receives it. He is currently about 3 weeks out, but for a fee, he will try to expedite it thru for you.
I am near Toledo OH. and the most I have paid is $800.00 for repairs. If it is just a bad encoder, it normally runs @ $380.00. New motors are running @ $1200.00. He does an excellent job, as I have never had a problem once I receive the units back from him. Tell him Joe Baker referred him to you.