Jammed toner cartridge

Hi--

I have a laserjet 1000 printer. Almost half of the times that I have
to change the cartridge, it jams (the cartridge is supposed to pop out
when the front of the printer is opened, and the door won't open
because the cartridge gets stuck).

Eventually, it pops out (not because I've done anything different...).
But sometimes it's a few days after I start trying to remove the
cartridge. I have had the same problem with hp cartridges and off
brand cartridges.

Any suggestions?

Thanks!

Nancy