Berre

I would take the SA hub apart for inspection and, most of all, a thourough cleaning.

Rinsing the hub's gut with diesel or kerosene may do the trick and get you riding again, but you never know if any parts (usually springs or pawls) might be damaged, worn or broken, unless you fully disassemble the beast. (Servicing the SA hub completely may take up to 2 or 3 hours, depending on the experience of the mechanic.)

It is perfectly possible for the handy man to succesfully disassemble (and reassemble!) the SA. Stick to the step by step manual available on the internet. It's not rocket engineering.

BTW: "filling" the SA hub with oil should be read as: "injecting 3 teaspoons of motor oil." Any excess of oil will be expelled and make a slippery mess. Eventually, oil spills on the rim's brake surfaces will make the brakes fail...