but all the teeth were missing off that side as well bar one - anyway, I know the gears are supposed to come in balanced pairs etc but I'm going to take my chances and not replace lots of gears (if I can help it) that aren't damaged. In fact I'm going to put the same synchros in as I dont think they're too bad either - so if you have a spare 2nd gear for a 519 or 644 please let me know 
Cheers
James