Only Cub Cadets - Model 1330

I have a model 1330. This lawn tractor has been used and abused for over 25 years. About a year ago it started to lose power in reverse. It will back up if I am backing down an incline and with a great deal of effort on a level. I have no problem with forward motion. My local dealer suggested checking the hydraulic fluid level, which I did. I added fluid to the reservoir, no better. Another issue is when I put the speed control in neutral and engage the brake the tractor starts moving forward. If I put it in reverse I can get off the tractor and it will not stall and will not move on it's own. I found a video on-line where a gentleman had the same problem as far as going in reverse. He found that there are two opposing ball bearing in the transmission that act as check valves. He was able to get replacement parts and his 1330 now seems to function normally. I know there are two linkage adjustment rods under the rear the tractor, could these be the problem?