I have a 97' 1200 S that I'm having the same issue with. The digits on the digital odometer/trip meter vary from can't see any digits at all to weak - digits can only be read in the shade. I have a new battery so it's not due to weak power supply.

I may try to change out the connectors as Javieret has suggested. If that doesn't work then I guess the mini tach / mini speedo mod that I've been contemplating will move up to top of my what's next list.