Who can rebuild a johnson 835894 power trim


My buddy is looking at buying a 17' Lowe boat with a 2004 Johnson 50hp 2-cycle. The outboard will trim up and down fine but leaks down really bad, there is no visible fluid leaks and the current owner has tried to bleed any air out of it but it still visibly leaks down when trimmed up. With it in this condition you can not run the boat on plane without holding the trim button in the up position which im sure will burn up the pump motor. Do anyone local rebuild these hydraulics?