200 Optimax Issues

Sounds like perhaps a compressor pump. Hard to say for sure though.

Check to make sure belt on top of engine is still intact! It runs the alternator and the air compressor. Without it your dead in the water! Had that happen to my old 150 opti few years back.

First go to your dealership that did the power head, then contact Mercury and their Customer Service desk if there is an issue which will require their direct involvement. Though if it was done in April, you should have a one year parts warranty, unless it was done under warranty that has since expired. Then you have a Public Relations and Customer Service item. Though in all cases start with a good reputable servicing dealership.BCB