Mowing how do I adjust my slip clutch on my rotary mower

[farmacist]

I have a 10yr old Ford 951B 5' rotary mower. How do I loosen the "slip clutch"? it is a yellow (aprox 8" diameter) clutch with 4 nuts. It does not seem to slip so I want to loosen it until it slips then tighten it up again but I have both loosened and tightened the 4 bolts but it never seems to slip. Is it adjustable? These 4 bolts are the only possible adjustment showing. Sorry I'm so DUMB. Thanks Frank

 

[Soundguy]

It's probably stuck a little.. you'l have to loosen the bolts.. then load the pto a bit.. perhaps mow a few feet.. should be obvious when it starts slipping. .. might put a couple pipe wrenchs on it and make it slip using cheater pipes and a push pull.. 2 handed job.. etc..

No dumb questions...

Soundguy