I replaced the front springs (Progressive) and put the recommended amount of 5W oil in. Replaced the rear shock with a Progressive 412. It's much better than it was.
I still have a problem where the front end bounces slightly up and down at 35-45 MPH. I tried the rear at all preloads, but I think it's front fork stiction. At any speed, the lower forks don't move when encountering the small irregularities in the road. They do respond over moderate bumps or when braking. When stopped, it takes some force to get the forks sliding. This is the "S" suspension.
Since this is my first K75, I don't know how much stiction is normal for the "sport" suspension. Any recommendations on fork seals? BMW or All Balls Racing? Others?
I did a quick alignment and torqued all the fasteners, which improved fork action somewhat. Nothing appears bent or racked, and the BMW mechanic who rode it several times didn't mention anything. I'll have to wait to clear out the garage (I have 4 bikes in it now) and tear down the front end to do a proper measurement and alignment.