HI, my JD D105 auto has 23 hours on it and up until this fall worked perfectly climbing hills no issues. Now even going up the slightest grade it can't climb. I replaced the traction belt and it is still doing the same thing. Goes up a hill fine in reverse. Was hoping a belt was slipping but I don't think so. No belt slipping noises. It seems like the transmission is not fully opening allowing full power?? Anyone have this issue? Thanks for any help. This has the RT400 transmission.