Howdy all,I was wondering if anyone had advice on my oliver...the problem was getting dsl in oil. I changed the lift pump...didn't cure the problem...so I took the hyd head off the injection pump. The tractor was running fine...just thining oil. It looks to me that it could just be the o rings around the hyd head itself....however the head does seem to be rather tuff to turn with a screw driver. My ? is should I just try the O rings...or try to locate a rebuilt hyd head or get mine done? The number on the bosh hyd head is 3173A. If anyone knows of a place to rebuild this that would be great too.....thanks.