1993 NH 2120 (the best), 1974 MF 135 (sold, but solid), 1947 Farmall A (bought, sold, bought back, sold again), 1956 MH50 lbt (sold, in 1980, darn it)
Correct fluid and correct quantity? Reverser linkage attached and functioning? I hear these are spendy to fix - you want to find a simpler problem. First rule out the mechanical, before you get to the hydraulic and/or electronic. Keep us posted.
Jim