I believe the ground speed going forward is slowing in my John Deere 6620 sidehill. In first gear you hardly know you are moving. 2nd gear would be pretty slow for combining beans. Combined most of this fall in 3rd. Road gear seemed a little slower too. Hydro always pulls the hills OK. Something I noticed today is that it goes the normal speed in reverse. In the YT archives it mentions a stretched cable from the hydro lever to the transmission. So, to fix that is it primarily an adjustment? Are there two cables (forward and reverse) or just one? Any one know the procedure for adjustment/repair? Thanks.