less than an hour between runs shouldnt see u have any probs,like i said its mainly from a cold start,especially in the colder months of the year,these boxes will lock u out of the lower gears till they're warmed up sufficiently.maybe just try getting it warmed up a little before the first run,or just take it a bit easier on the shifts on the first run.

u really have to find out what broke this time & also what did fail in the synchro system the first time around?

maybe even try backing down a little on the clutch specs if your not making an overly shitload of power over stock on the motor.