I accidently put the hydraulic lever on my 1964 MF135 into continuous pumping when all I had on was a Transport box. There seemed to be a clunk and now I can only lift the box one inch from the ground. There is a small amount of oil around where the single external hydraulic feed pipe connects under the seat. The oil level is OK. Any Idea where I should start to look. I have never delved into the hydraulics before so any help would be appreciated.