MacBook Pro keyboard intermittant fault

Last October (shortly after I'd installed Catalina) the R-T-Y-U-I-O keys on my keyboard stopped working intermittently and sporadically. If I rebooted, or reset NVRAM or PRAM or SMC they'd start working again. I took the machine to the local Apple rep and the guy there said that I should reinstall the O/S, see what happens, then bring it back if I still had a problem. Installing a new keyboard would be a financial write-off, apparently. I reinstalled the O/S and Lo! (I'm reading my kid LOTRs) all the keys started working again with no problems. That was three and a half months ago and since then the machine's been working fine. But today the problem has come back again - typing this is a pain - sometimes the keys work, sometimes they don't. I can't work out if it's a hardware or software problem, although I suspect it's something to do with the software. But I'm not an expert. On line I've seen some posts with similar problems. Is this a 'thing'? Is there a solution? Has anyone else had the same problem? For the last six lines of writing this we seem to be back to normal again. But if things go true to form, one of the keys will stop working, followed by the others. I'd appreciate any feedback anyone has.

Thanks.