CB350K2 Clutch slipping

I bought this motorcycle last year. It had been rebuilt and nicely painted but I have needed to troubleshoot quite a few problems. I didn't notice clutch slip on my first few rides but engine wasn't making good power. Now that the engine is running better I find the clutch slips when I give it some throttle. I didn't know what iol the PO used so I have changed it a couple of times and I use 10W-40 mineral oil that's okay with wet clutches. One thing that surprises me (and this may be a clue) is that lever pressure is surprisingly light. My CB77's clutch lever requires a lot more strength, and that's made me wonder if the CB350's clutch springs are weak or even coming undone? I've tried adjusting the clutch release adjuster then the cable, according to instructions, and with cable adjuster too slack the clutch drags, and with the cable a bit tighter it doesn't drag and gear changes are sweet, but the clutch slip persists. Before I take the r/h cover off to examine springs and plates I thought I'd run it by you people.