No Reverse on OD tranny

[fast fredy]

Morning all Have a problem .. yesterday everything worked as it should.. This morning I try to back my wagon ( 55 wagon 272 overdrive) out of the garage and have no reverse , other gears work . linkage appears to go into place but no rear movement when releasing clutch ... I took the linkage off at the trany to be sure it is engaging properly and it seams to.. In regards to reverse lockout does it keep the linkage on the sideplate from moving or will it move but not move internally thanks FRED