My 4100 has had the drum and toner installed new, when i copy or recieve a fax it blank/very faint. can you help?

When you remove the toner and drum unit out of the machine look inside where it was, look up inside that spot where the drum was and you will see a glass window that is about 3/8 of an inch deep and maybe 8 to 9 inches long, it is likely a film of toner is on that glass blocking the laser light from hitting the drum properly. Just use a dry lint free cloth and wipe that glass down and you should be good to go. Remember look up in the spot where the toner was it can be easy to miss it.