Id wadger if he would listen and put the ATF in it like its supposed to have he would find it a lot easier to shift.
I rebuilt 2 of them for a friend of mine for his Feather Dusters. ! had the ATF put in it. The other 1 he wanted the Mobil 1 syn in it. The 1 with the ATF shifted fine, the other 1 with the M1 would hardly shift into 2nd gear untill the fluid was hot. We drained the M1 out, refilled with ATF and that 1 worked just like the first 1. They DONT like the heavy lube...I know of 1 in a Hemi Superbird that works just fine in it also.