Lock mechanism won't turn

I’ve got a Craftsman 6 Drawer Side Cabinet that’s probably about 10 years old. It’s model number 706.813360. The lock mechanism has gotten progressively tougher to turn and has finally stopped turning entirely. I was able to remove just the lock itself, but now don’t know if it’s possible to disassemble further, and I couldn’t immediately find a replacement lock mechanism online. Any ideas or suggestions?

I called Sears and while they answered the phone, they say it’s obsolete and they no longer stock parts for this product.

Cabinet with lock and top drawer removed:

Lock front:

Lock back: