Tranny Problem

i have heard that its a common problem for the 85 GT manual transmission to slip out of 1st and 3rd...i have just changed the fuel pump and its now runing but i ran into a problem that if i don't shift the perfect way into 1st gear when i let the clutch out it usually doesn't catch and i hear the wonderful grinding noise...i have bled my clutch do u think this could be a fluid level problem or syncro or something i can fix cheaply? any advice or suggestions on why its acting up?

had the problem with my 88 gt had the shift cables adjusted and that fixed it