Hello, I'm wondering why my newly acquired 750 will print just dandy on 20# bond but when I print on 28# laser (through the MPT), the toner flakes off in mostly the black areas. It also seems to dither the images more than I would expect (even for a 12 year old printer). Oh and how would I go about figuring out what model I have? It had a duplexer, hard drive and 196 MB of RAM but I can't seem to find the designation anywhere on the printer... Thanks in advance!