I have the Colnago master with DA7400(SL-7400) which can be run as SIS or friction. So far I had no problems at all, and it still runs real smooth. I do regular maintenance or occasional adjustment for sure. If you have your model number, you can go to Shimano web site and look for service documentation on it. Very simple to compare todays shifting system but very effective imho.

This is link to the search page for the manuals and documents. Hope that helps.

si.shimano.com/#/