My mower is a Craftsman YT4000, model 917.288561, approx 2010-2011 year. I was mowing and attempted to switch from reverse to forward when I heard a loud grinding noise coming from the transmission and it will not go into forward or reverse. The repair shop says it has a sealed rear end and will have to be replaced at a cost of $250 just for the used part. I was reading on other forums where some so called sealed rear ends can actually be pryed open and put back together using a new gasket and some RTV glue. Does anyone know if this one can be done that way? Also does anyone have ideas what is wrong with the rear-end/transmission? The repairman has ruled out any pulley or belt issues, he said its growling internally.