Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
How far apart are the indentations? if they repeat in a sort of pattern, or if they are just single indentations, the distance apart on the page will indicate the circumference (or distance around) of the rotating element in the printer that is causing the indentation.
That component will have to be either repositioned/re-seated (if it is simply a trifle out of place or out of adjustment) or in severer cases, will have to be replaced altogether.
It could be (without my seeing the indentations, or knowing their distance apart on the page) anything from the drum/developer/cartridge, to the fuser roller(s), down to a paper feed roller somewhere.
There are tests that can be done, to determine where in the printer the defective component is likeliest to be located. One of these is the 'half-way' test... would you like to try it? if the distance apart of the indentations is not sufficient to locate it, this would help a lot.
Let me know further details, and I will help you further toward a good solution. Thanks.