'85 GT150

I have a goofy tilt/trim problem that has existed for a LONG time according to the previous owner.

When I trim ALL the way down at the moment the cylinder bottoms out, the pump make a squealing sound. At that point, my tilt function is locked up. The pump will spin, but the cylinder will not extend for 30 seconds. After 30 seconds it works great again until it gets bottomed out.

The fluid is full
I tried to bleed the system last year and that did not help.

I can live with the problem, but I would really like to fix it.

Thanks,
Greg