Here's my situation. I bought a very low mileage rebuilt race C4. The person I bought it from was getting out of racing and just wanted to sell it off. He said that it was a fully rollerized trans with kevlar bands, hardened input shaft, etc. Due to my ignorance on the matter, I wasn't aware that the input shaft was supposed to slide out. I thought it was held in by a C- clip or snap ring. With the trans I bought the shaft comes out a short amount then stops. I didn't realize what this issue represented at the time of purchase. I disassembled the trans to discover that the input and output shafts have crashed into each other. Both shafts are chewed up pretty good. It seems that there is no getting the input shaft out due to heavy burring. On a positive note, the trans is rollerized and the band that sits directly behind the pump still has the printing on it which does say "Kevlar" on it. I'm not 100% certain that the seller knew of this situation with the trans. I've spoken to someone else who knows him and they said that he is a straight up guy. Also, I haven't contacted him yet about this but I plan on it at some point.
Can I press the input shaft out or do I risk causing more damage?
Can the shafts be machined/ repaired?
I've heard that sometimes the aftermarket shafts can be a little long compared to the stock shaft and that this crashing issue is not uncommon.
What would cause the shafts to crash into each other to begin with?
You will need a new forward clutch drum. The input shaft has started to take out the splines allowing the input shaft to go too far into the trans and thus mashing the two shafts together. You should also get a new shaft. Performance Automatic in Maryland will have those parts. Don't worry about the output shaft.