I bought a b7100HST for $1400 in dec. with only 790hrs, with low engine compression on #1 cyl. The dealer said #1 cyl. was bad and needed a complete rebuild or just #1 sleeve replaced. I've put $700 into it and found the valves in the head were sticking or just not closing. So I just had the head tested, cleaned and valves redone. I put a oil pressure gauge on it to be on the safe side, and have noticed the oil pressure starts at 45PSI about 1/4 throttle and 55PSI at 1/2 throttle. After its ran for about an hour I noticed the oil PSI goes done to 30 and stays there, but when I put the throttle back down to 1/4 throttle the PSI falls to 10. I think I need to replace the oil pump, just not sure how much time it'll take to replace it.