The majority of non receive issues are phone
3 conditions must exist for a fax to receive, the phone line voltage must be high enough, the phone line current must be high enough the the DB gain must be correct.
A fax receive should be viewed in the same way a remote controle works.
When you send a fax, you manually access the phone line when you select send, you connect to the phone line, normally via a relay. Once that physical connection
is made, it can send anything. Maybe not well, but it will send.
Where as receiving is an electrical signal that activates the machine. If your phone line is not up to standard, its like haveing a remote control
with weak or dead batteries and trying to turn on your TV
with those weak batteries in it.
Issues, simply a bad phone cord between the machine and phone jack. Some resistance may have acrured over the years. The phone jack itself may have a poor connection.
A staticy phone line will cause a fax not to pick up. Plug a phone into that line and see if there is any noticible static.
Multiple devices plugged into the phone line with the fax machine. ETC an answering machine, credit card
machine, etc can cause more of a draw on a shared line, if that is the situation, at least for a test, remove everything but the fax machine from the line and see if it receives then.
Rarely if the machine can send and not receive is the machine an issue.
Have your phone lines checked well and that sould resolve the issue. And make sure the line is not plugged into the extension or phone jack on the machine, but plugged into the line jack. That is also a common problem.