Trim still going down

[steplift20]

I had a leak coming from my end cap, took it the the Mach and he gave me a new cap and seals I told him that it doesn't stay up it comes down very slow and thought that the fixed leak would fix it it didn't ,I see know leaks and was wondering what would cause the trim not to stay up, it's a 1988 mercury out board 150 hp. Thanks