You might check the electrolytic caps in the power supply section.
Has it sat for a long time? You might want to replace those as they do dry out eventually.
My 2510 did something strange one time. I let it set for about 5 years, took it out of the closet, hooked it up and the transmit and receive worked fine but no display! I took it apart and checked everything, could find nothing wrong so I put it back together and left it on the rest of the day. I tried to find a display to no avail so I put it back in the closet.
About a year later, I took it out, hooked it up and BINGO!!! it worked fine!! Go figure, I gave it to my brother and it works great. It wasn't a problem with my power supply as I even plugged it into a working mobile in my car and everything except the display worked!
The only thing I can figure is the power kind of 'rejuvenated' the caps and a LCD! I told my brother to turn it on once in awhile and he has had no further issues!
I have been into electronics since I was a kid in the 1960's but electronics still do what it damn well wants to even if it defies logic, LOL!!!
I wouldn't wory about it unless it gets worse!
Let us know what you find.