1979 Sears Solid State TV popping

[kb12]

Hi, I am new to this forum and to vintage tvs. I just bought at 1979 solid state sears TV for $15. The picture looks great but a couple weeks ago every time I turn it on it makes a loud popping noise. Sometimes the noise is faint, sometimes it is really loud. Nothing changes in the picture though, still looks good. What could this be? Is there anything I can do? Thanks for any help you can give.