can anyone give me some advise on a hydro problem  before I tear into it??  we had just finished combining rye in a wet field where we were having some close calls getting stuck so the hydro was getting a good work out that day. Last round with a full hopper started to get stuck pulled back on the hydro lever to back out that worked fine but when we went to go forward again nothing. Now the combine only goes in reverse and not very fast.The shop manual tells to switch the 2 high pressure valves &amp; see if that switches the direction. If so replace high pressure check valve. I was just seeing If anyone else has had this problem &amp; what the fix was. any info would be very helpful.