New to me tractor that had been sitting outside for a while. and the diff lock lever won't budge, and I mean not even a millimeter. The diff lock is not engaged, went in sandy area and one tire would spin and not the other. didn't have a ton of time this morning to look at it but looked underneath and nothing on the linkage was glaring at me. Idea's on where to start? Any danger of damaging something internally if i were to hammer on it a bit to try and break it free?