That's an old one: ftp://ftp.panasonic.com/pub/panasonic/business/office/spec_sheets/kxp3626_ss.pdf
http://panasonic.net/pcc/products/printer/download/p3626download.html has utilities for DOS and Windows 3.1 and drivers for Windows 95, 98, 2000 and NT.
So it's not really amazing if something is wrong with it after 10 years or more.
http://panasonic.net/pcc/products/printer/trouble_shooting/ offers troubleshooting (in the right column).
And usually back then they came with a printed user manual that includes a chapter about problem solving. Indeed, I see that in the online version (just page down): http://www.fixya.com/support/p375028-panasonic_kx_p3626_matrix_printer/manual-8364
If no luck, it might be time for a replacement, unless Panasonic tech service still supports it.
All the lights on the front panel keep flashing, eventually after switching off and on and leaving switched off for a while it sometimes goes away.
Does anyone know what the problem may be and what the solution is?