NP205 problem

[orangeuavol]

I have a NP205 mated to a TH400 in my Blazer and I am having trouble getting the TC to 'engage' in 2hi and 4hi. I can put the TC into 4lo with the tranny in park, shift into drive and all is fine. When I try to put it 2hi or 4hi I get an awful grinding noise when I put the the tranny into any gear. Any suggestions as what the problem could be? I've checked for loose motion in the linkage but doesn't seem like much if any. The shift rods seem to be engaging the detent pins but the passenger side rod does have some loose motion. the inside rod doesn't have any loose motion. Is there a trick to shifting the 205?

I bough the TC and tranny from a board member and said it had been rebuilt but had sat in his barn for a year or so.

Thanks in advance.