Well, the problem reappeared after a backwash. Interestingly enough a day later the top to the multi-port started leaking, where the handle / diverter bolt on. Hi-ho, hi-ho it's to the pool store we go (whistle along).... Grabbed a new o-ring, no more leaking from the multi-port, or out the waste port. The top did seem to rest a bit higher, before I screwed it down. We'll see what happens after a backwash. What I'm thinking : the old o-ring was worn enough where the pressure was high enough to lift the top enough to let crud slide under the spider gasket. I can justify anything.... I've thought I've had this fixed a bunch now. *sigh* stay tuned...