did the garage bleed the clutch system as well?
Also has the gearbox oil ever been changed? if so do you know what oil was used as these gearboxes need a GL-4 type oil. GL-5 will attack the yellow metals, as far as I'm aware these gearboxes have brass syncros.
I've also read that the clutch throw out fork & pivot bolt can cause issues on these but that is a transmission out job so would be the very last resort of things to check
