I like @vinylvin 's suggestion to try cleaning the contacts. A zero cost approach to the problem is a good starting point.
Only YOU know the sentimental value of this unit. I spend one day a week with my tech of 25 years doing exactly that -- keeping old stereo gear with an emotional attachment to the owner(s) from ending up in the dumpster. I refer to it as my "involuntary not-for-profit organization" in that we bring in about $1 for each $3 we spend taking care of business. We make sure the customer is informed of "current market value" of a "questionable" piece and let them decide if they want to make the investment. It's pretty rewarding to see grown up's brought to tears when a deceased family member's, or close friend's unit comes back to life. Or, push the power button on piece that went to college with them and survived multiple divorces, light up and play music once again.
IF the cleaning does not solve the problem, I'd suggest contacting someone in your area that does repairs, and see what their opinion (including a rough price range for the repair) and see if your attachment to the unit exceeds this price. $300 spent on a piece with a "current market value" of $59 (in working order) is $241 spent for sentimental reasons. I can think of worse ways to spend money.