I'm in the process of trying to rehab a Diamondback Crestline touring frame. I assume it's from the early '90s. I'm having difficulty getting a cartridge BB into the shell. The BB shell is threaded in the right directions for a standard, English-threaded BB (left-threaded on drive side), and it seems to be the correct diameter, but it feels like the threads aren't quite matching on either side. The cups will thread in about half a turn, then come to a halt. It's possible that I just gunked up the threads during the re-paint, but before I start applying cutting oil and brute force, I thought I should check here to see if anyone here might have some knowledge of peculiar threading on these frames. Anyone?