Looking for a second opinion on the gearbox on my '89 Corolla.

Anyone got a pointer to a Toyota transmission specialist? Googling for the particular symptom that's irritating me lately--popping out of 5th gear--has revealed that some 5 speed manual gearboxes have an easier fix than swapping out the whole gearbox. My mechanic doesn't know of this, but maybe someone who specializes in Toyotas instead of Saabs has a better idea.

The specialist can be anywhere in the Northeast Corridor, as the car is quite drivable--I just drove it from New England to Knoxville, TN and back in July--and I'm willing to go places to talk someone who knows Toyotas. If you know of a real guru I should drive to say, Chicago for...well, I'd do that, but it's a bit more of a stretch.

Thanks for any info; please comment, email, or text.