Annoying squeak in microArranger organ "programs"!

[ddmetzger]

I am using the microArranger for church services but I have found that many of the desirable "programs" (aka voices) have an annoying very high pitched "squeak" which seems to be triggered by the act of depressing a key. It occurs on about 70% of the "programs" but doesn't always sound the same. The exact pitch of the squeak does not seem to be related to the pitch of the notes being played.
It is particularly noticeable for "programs" such as "ClassiClick". It is correlated with the speed of the Leslie effect - slowing down and speeding up as the Leslie speeds up and slows down. It sounds very much like a real Leslie with squeaky bearings.

Is there some effect added to the Leslie to simulate rotary noise?

Any help would be much appreciated. This has been so bothersome for organ "programs" that I have started using only synth voices for the services.