The only problem is a full CLA on a Prontor shutter on these cameras is far more than it's worth. I pisked up a mint Prontor-S (post WWII) for 2 ($3.20) the other day it's never been used on a camera, another with a brand new Novar for 7 and a third with a Kershaw lens for about 10.

So I'd say go for a self clean initially it's revived many shutters for me all of which still work perfectly some quite a few years later I tend to use a few drop of Isopropyl alcohol initially into the shutter mechanism them fire it off to free it up. This often does the trick and it's rarer I do a full flush clean.