Perfect Pass issues

Last summer my perfect pass started not holding speed. It will fluctuate 2-miles an hour.

I have an 2006 Supra 24SSV I replaced the PP about 3 years ago to a GPS model.

When I had the boat de-winterized I asked them to take a look at it and this was there response;

Check perfect pass for function
Description:check perfect pass for correct operation
Resolution: Pick up from storage, Water test for perfect pass, it does have a variation at slower speeds, this system works better at 18 miles per hour plus -- That is what boat is designed for. haul out and take back to storage

It didn't use to do this, why is it all of a sudden fluctuating now, and is this an acceptable response or should I push back?

Plus they charged me $220 to look at it which I'm on the fence about paying if it is something they should be able to fix.

I appreciate any educated assistance........Thanks

(I'm assuming this is still cable controlled in '06). Check the cable between the servo and the throttle. Mine was a little rusted and sticky this year and made the perfect pass work exactly like that. I just removed it, cleaned and lubricated and it's fine now. If you google PP troubleshooting they walk you through a test for this but basically you turn the engine off, give it half throttle, and turn the servo knob both directions. The throttle must move IN BOTH DIRECTIONS to correspond with you twisting the servo knob. If it's corroded and sticky it will only move in one direction.

I’ve got a 2006 Sunsport 24V. Essentially the same boat and it was the first year of the DBW, Drive by Wire. I’m still using paddle wheel on mine but the GPS uses the same logic to control the engine. Mine started doing funny things. In that year PP was patched into the engine computer main harness unlike the 2007 and later in which they had a real harness. On mine I found where they patched into the 16 pin harness that runs behind the engine computer. I found light corrosion on a few of the pins. I cleaned them up and it works like a champ now. I believe the PP modules are very sensitive units.