1998 GMC Jimmy radio problem

I have a aftermarket radio with cd player not sure of name of radio but the volume button is starting to not work it started with the down button not workin had to use a pen point to push the button to make it work couldnt just press it. Now the up button is starting to do the same thing. I am wondering if it is the radio the face plate or just the hook ups. If it is one of these would it be easier to put a factory radio in or fix it. The radio in it was in it when I bought it. The problem just started with the up just a couple weeks ago the down has been that way since I bought it almost a year ago. The down button used to be able to press it real hard and would work but no longer doing so.
Thanks