A few weeks ago, I posted a link to fixyourownprinter.com. My trusty old LaserJet4 was jamming, and these guys appeared to have the fix. I promised a follow-up. Here it is.
These guys rock! I ordered the kit via the Web. It arrived a few days later. It included a very clear instructional video on CD-ROM and a kit that included all the parts I needed. The video walked me through every step of the repair, which involved partially disassembling the printer and replacing a half-dozen parts. All told, it took about two hours, and the result is a printer that works just like it used to.
Two thumbs way up for these guys. If you’re having problems with a printer, check ’em out.
Ed Bott 
More power to you, Ed! I agree that the kit and video provide all you need to get the job done, but I’m a klutz, and I had trouble getting everything in place. (Who knew there were so many spring-loaded pads in a LaserJet 6L?) It worked eventually, and worked well, but the biggest lesson I learned is that servicing printers isn’t a career path I’ll willingly take. Thanks to fixyourownprinter.com for teaching me that!