Victa self propelled clutch adjustment?

I have a Victa 550mm self propelled mower, and the rear wheels don't drive when the clutch handle is pulled in. The cable adjuster under the air cleaner was at max adjustment, so I backed it off, and moved the clutch actuator arm around a couple of splines to give it more bite when the handle is pulled in. Even after moving the cable adjuster a few more times, still no drive to the wheels. Do these mowers have a history of problems like this? My next move will be to pull the clutch assembly apart to inspect it for wear, etc. Any ideas? Thanks.