Actually, I've seen many Honda trannys with synchro damage symptoms. But...it's actually the input shaft bearing that went first, giving enough play in the shaft to pop gears out and/or grind. Also, the bearing races on many are a plastic composite and when they shatter the little chucks can plug the lubrication holes in the shaft. If you catch it fast enough, you can rebuild for as little as 50-100 bucks for the case bearings. IMO, you should always tear down first before buying a new one. Even if it's fucked you will have tons of useful salvage parts. Final drives and good gear sets will fetch enough $ to pay for your new tranny at times.