I agree with both Jed and Kenny....
If the machine is indeed a belt drive and it won't drain or spin, but continues to idle, then my first suspect would be the wigwag (aka control magnet) just like Jed said.
If the machine just stops dead, then Kenny is likely right as well, as dead spots do commonly develop in timers when contacts wear/burn out, especially machines of that era. When timers begin to go bad, they will first exhibit momentary pauses in motor operation as the timer advances, but they resume and continue on. As the failure of the timer progesses, the momentary pause turns into a full-blown dead spot. This is usually worst in a cycle used frequently. For example, if your friend uses the Perm Press cycle mostly, there may not be the same dead spot on the normal/cotton sturdy cycle. If her machine is truly shutting down completely, suggest that she try another cycle to see if it will complete one she doesn't use much. As Kenny says, giggling the timer knob can make the machine re-start, but as the spots get worse, sometimes even that doesn't help.
The wigwag is not a big deal to replace, however I would recommend a repair manual for a reference (they can be had cheaply on ebay). If the problem is the timer, that is an easier repair, but possibly more costly.
RE timers: From 1976 thru 1986, I'd guess 95% of all belt-drive Kenmores used one of three timers. Because so many bazillions of machines were made during that time, there are lots of timers available. Balcum on ebay sells tested and guaranteed used ones for as low as $10 (you have to make an offer). I bought two recently, which would be a great way to go for your friend if money is an issue. She can change a timer easily (the repair manual is a help there too).
If you can get us the model number, I'll tell you what timer to look for (if that's the problem) and exactly how to swap it (one of the newer replacements of the three requires a jumper wire to be spliced for spray rinses to work properly).
Good luck - I'll check back from time to time to see if I can help further.....
Gordon