Deere 450C grinding gears and no low range

First, thanks for allowing me to join this group, looking for some experienced help with my new (to me) John Deere 450C Did a search and could not find any information that I was specifically looking for so...... Bought a 450C to clean up some property I own, as near as I can tell, about a 1976 model. motor runs great, acceptable undercarriage and for the most part does a good job for what I bought the machine for, however.... I have no low range, hi and reverse work fine but when I shift to low, it's like it goes into neutral. Linkage seems to be adjusted fine but nothing in low. Also from what I think may be a separate problem, with the clutch depressed can't shift 1-2-3-4 without grinding gears unless the motor is stopped. Clutch seems engage/disengage normally. From what I can tell from other posts is there is a hydraulic pressure adjustment inside the bell housing.