Why would the fax on the other side complain the print is to light

Faulty Drum

When you see light print it can be from a few things. This is basically a laser printer with a fax machine so the same problems exist in both. The most common cause by far is simply low toner. If you take out the toner cartidge and gentl shake it side to side then put it back in. Now try printing again. This should be much darker. This may only last a few dozen pages (but can go a quite a bit more if you are lucky) but it shows you that you need to get a new toner cartridge. The other causes can be a image setting in the fax. In the control panel it will show you a setting for how dark it will print. Normally it is in the middle of the range. The last common thing is a fusor wire. This normally shows up as a error first but it can slowly fail. The fusor is the heater that bonds the toner to the paper. If it doesn't get hot enough then not all the toner sticks and you get light printing.

Normally the problem is low toner.

Your thermal head is defective. No replacement parts available.

You should get the Number of the Companies Fax Number and complain to your Telephone Provider, that your constantly receiving fax messages from a Company that's obviously dialing the wrong number.
The fact that they're not getting any replies from you surely should lead them to realize that they are dialing a wrong number.
Then perhaps the Telecoms Company can put a Block on the Number from calling you again.

Worth a Try :-).

Open up the document feeder and look for a trapped down or sluggish switch

we cannot figure out why the fax/copyer always prints things out very light you cant see any thing that gets printed out on it

your machine most likely has toner spills in it.
if you send faxes face side down follow these instructions ;
1- take out toner
2- look for thin glass strip on bottom inside the machine
3-wipe clean

if you make copies side up then do the same except look for glass strip on the upper side of machine

are copies light too? if not then it is sending fax, but most times it is inferior ink or drum causing the problem sometimes damp paper (try printing on reverse side as well)

It sounds like you have a bad scanner. Depending on the age of the machine it may be under warrany. Even if it is not, I would call Brother and complain. I know in the past, they did have some scanner issues that they wewre covering even past the warranty period. Their number is 1-800-284-4357. Good luck John