Simrad Wheelpilot Mount Slipping

[Joe500]

I have a Simrad WP32 wheelpilot mounted on the steering pedestal for my sailboat as per the instructions. The wheelpilot is held on by two rubber bands that wrap around the pedestal as shown in the pictures. Actually, they are rubber sleeves that are threaded over very long clamps like the kind you use for plumbing.

The problem is that in any wind above about 10 knots the wheelpilot tends to slowly slip downwards along the pedestal until it is no longer centered with respect to the wheel. I've tried tightening the clamps but it doesn't seem to help. I also tried glueing the plastic pedestal mount to the pedestal directly but that didn't hold either. Does anyone have any other suggestions for how to keep the wheelpilot in place? Any ideas would be appreciated.