On my OMC 1700 the stator was bad and could not find another so I wound my own. Took all of 2 hours which was how long it would have taken to look for one. Always worked after that. Also check your rectifiers and regulator, what seems to be a stator is often in either module.
If your Dad's machine does in fact have a stator verses an altenator (not familiar with this particular machine) here are a couple things to check before you tear into it too deep:
1) Check the two wires coming from behind the flywheel for voltage. If memory serves correctly this should be between 28 and 32 volts ac with engine running wide open throttle(wot). (This is for a Kohler engine, but I believe the principle is the same regardless of make).
2) If no ac voltage across the stator wires check for shorts in the wiring where they exit from behind the flywheel, if wires are OK, you likely need a new stator (but don't overlook the flywheel magnets).
3)If above checks out OK then test output voltage at the rectifier/regulator, should be 12-14 volts dc at wot. If this checks out OK then your problem is likely either in your wiring or ignition switch (check for corroded/burnt terminals)
4) Still nothing? Here comes the crappy part ( before spending money that is) check and clean all grounds and connections, generally speaking these are very durable components and usually don't fail with-out outside intervention (hooked up jumper cables bass ackwards etc) where-as corrosion is common. Often times replacing a part appears to fix it, but in fact all that happend is ground contact was re-established during replacement (been there done that (more than once actually) nothing like spending good money after bad).
Hopefully this helps some and with luck, saves you a little coin in the process.