Roland sh-2000 service advice

[Elkhorn]

G'day,
I have been working on my very neat Roland sh-2000.
Overall condition is great, but after a couple years I have run into some issues.
I have had to recently run through the tuning process outlined in the service manual, I don't have a oscilloscope so I did so with using a meter for frequency measuring Hz, which was tedious, but the process worked very well.
The issue I have now is, despite the manuals suggestion to wait for the unit to be powered up for five minutes before the tuning process, I have to now wait around 20 minutes for the tuning to settle down and play the correct tuning over the whole keyboard...
Infact all functions seem to need the warm up time of approx 20 mins before it plays as it should (ambient temp late 20 degrees celcius)
Afterthis time it works perfectly and sounds great.

My question os what components should I replace to fix this issue??
I've read other posts and forums regards issues with the sh-2000 and power stage seems fine. And mostly seems in great condition otherwise.
It is the earlier serial number with original filter.

I would be greatly appreciative if some guidance could be offered as to what components I can replace to fix this issue.
Best regards
Elkhorn