Adcom 535L upgrades?


I have an old Adcom 535L amp (60wpc) from the 1990s. It's a utility amp and actually sounds decent if a bit grainy in the mids and highs. I'm not going to try to sell it, as it doesn't promise much on the used market. 

I'm wondering if anyone has replaced caps or other key parts in their older Adcom gear and if so whether (a) it made a real difference and (b) how much it cost? 

Thanks.
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@johnss Thanks for the suggestion. I'm probably not capable of DIY on this, but knowing what might make a difference helps a lot. Appreciate it.
OP it was 65.00 for parts I did the work. That was a 5500, too.

I would put it on the shelf, UNLES there is something wrong and you want to spend the money..

It's a DIY for sure but having someone do it.. You'll never recover the money.

People can say what they want. A LOT of people used and still do use The OLD and the NEW.. Some are all tricked out.. they can sound very good.. especially for the money.. They do run a little warm.. Actually the warmer the better.. 555 was real popular because you could mono it and get some pretty serious power for the money once again..

Regards
Yeah, thanks @oldhvymec 
Appreciate it. I have a buddy who loves audio but can't really afford to do much right now. He's turning 50 this year and likes my Adcom. Either he or my son will get a present from me, and if it's possible to polish a radish for not that much money, it'd probably make a nice gift. My buddy has very decent Paradigm bookshelves and some Schiit gear, including a decent preamp. If it doesn't break the bank for me, seems like a no-brainer.
Have you looked inside the amp? Leaking capacitors etc..? Might just need a good cleaning the 535 while the lowest watt was considered one of the best performance for the money at the time.

https://www.stereophile.com/solidpoweramps/adcom_gfa-535_power_amplifier/index.html
I have looked inside. Looks fine. Works fine. I'm in the Tweak-light Zone on this one, for sure!