One of my X-700's ( I have 2) has the same frame counter problem but I just ignore it. Both cameras were bought new in 1984 for a trip to Europe. Both had a capacitor failure within a month of each other last year. I replaced the capacitors (not hard) and now they are working fine.
I kind of panicked when they both went bad and started buying SRT's as a mechanical back up.
At the same time I saw the ad for an XD-11 body with a buy it now price of only $34.00 so I couldn't resist. I'm glad I didn't.
I need a huge camera bag and more arms to shoot with them all.