I have a Lazer HP 23 Kohler bought new in 05/04. It now has ~ 155 hours. Last Saturday I noticed fluid on top of the hydraulic tank. I took it to the dealer and the mechanic tightened the hydro filter about 1-1.5 turns and found a line to the left wheel motor almost off. He said the foamy-looking oil tipped him off that air was getting sucked in. He put a hose clamp on the line, filled the tank, and I was off again to mow. Last night I got more oil on top of the tank a couple of times. The oil was not foamy like it was Saturday. The level still looks ok. Any ideas?