your first and reverse gear select sleve is probally fkt.
I had grinding problems too, but it only happened sometimes, most of the time i just changed slowly, but apprantly this is a common problem so i wouldnt be to worried about it. but when my gb was opened my first and reverse select sleve was demolished. along with my 2nd gear and 2nd gear syncro lol.
has he given u a quote yet? caus toyota wanted aprox 2g for labor alone and parts extra LOL!
Heres the new select sleve compared to the old one, left is new one and old as u can see the dog teeeth are all chipped LOL
here's a closeup
even in this condition it didnt grind as much as u say yours does, or maybe the dealer ****tin ya :P caus it took them half and hour to figure our which select sleve i was holding, even with the mech that specializes in gearboxes lol. one dude even said the celica gearbox is unbreakable because it has these "things called syncromesh" excatly what he said to me hahaha! which prevents it from grinding and it can only break if i push it too hard but no grinding, man was i laughing, so i ordered my stuff and left.