50 SERVICE error on my HP laserjet 4MV

Question

I stored this machine away about a year ago it was working fine. I pulled it out the other day to begin using it again and this service error showed up. The printer was just sitting in a closet for a year unused. Toner cartridge fairly new. No previous problems with machine other then it running hot which it had been doing since it was originally purchased. Any help with fixing this problem would be greatly appreciated.