I suggest getting the local priest to do an exorcism before you end up with 20 mowers haha
Looks complete, just dirty. attached is a manual which should be about right.
This is copy and pasted advice from another thread with regard to this sort of engine:
The carby can be a pain - it has a diaphragm which probably hardened years ago. It should be part number CAM506 (GA spares - any mower shop should be able to source) Be careful when disassembling the carb - it may have a hardish to source teflon washer and pin. Therefore, work over a piece of newspaper and look very carefully before completely removing the carby off the top of the tank and don't lose it.
Check the spark plug, if it is choked black and sooty, it is possible there is an issue with the carby and you will need the repair kit. Could just be the clogged filter though
Buy the cheapest oil you can find (old briggs aren't picky) and dump the old sludge. Capacity is around 600ml. Autobarn normally have a 15w40 out for $10/5L.
Air filter - looks like GA "air106". If the old one isn't rotten, wash it hot soapy water, dry, then recharge with 30-60ml of oil (chainsaw bar oil if you have it). The oil catches the dirt.
You could order most if not all of these parts from Bruce here at ODK - will be cheaper than mower shop most likely, if you aren't in a rush
