Is the Voyager a whirlie? If so, it may be a failing spindle bearing, in which case I doubt there's much you can do about it.
My 501 was a whirly, but I'm very sure that my noise came from the alarm sounder. During the fault, you couldn't get a reading (this was the bit that disturbed the crew) on the shallow range, but it was OK on the deep range but this wasn't much comfort when nosing into a shallow bay.
I've just realised that in my previous post, I talked of preserving the paddlewheel but of course this belonged to the Stowe Navigator 1 which was replaced at the same time.