Simrad AP28 Rotary Drive Unit Failure - Help Needed

[Quadrille in JB]

My friend is currently about 950 nm from the BVIs, having departed from the Canaries.
The rotary drive unit on his Simrad AP28 has failed and he has asked me for help in locating a replacement drive unit that he might be able to install in the BVIs. This unit is installed in an older Pearson 44' Contessa.

His quote:
"Autopilot...magnetic clutch is gone...have been jury rigging it since the MED...if possible I need info on a rotary actuating autopilot actuator...it is a Simrad AP-28. The actuator has an electric motor..connected to a reduction gear..and the other end of reduction gear has a drive shaft sticking out the same side as the electric motor. On that drive shaft is an electromagnetic clutch which magnetically joins a metal disk with a chain sprocket on it. Not sure if this is an original Simrad part or an aftermarket part."

If anyone has any idea of where we could find a replacement we would be very grateful. It's not much fun hand steering a heavy boat for weeks at a time.
thanks in advance,
Bill