Re: Evinrude Lightwin 4hp - what year?
Here's a link to OMC parts catalogs, as luck would have it they go back to '69, which is indeed your motor's year of mfr.
http://epc.brp.com/DEFAULT.ASPX?BRANDS=EJ&LANG=E&DEALERLOCATOR=NO
Wal-Mart may have the stuff in stock, pretty sporadic around my neck of the woods. They have the empty spaces for the parts but they're not restocking. Also check your local NAPA as they usually have a small line of outboard parts in-store, or can get them for you.
Here's a good FAQ from this site on waking up a sleeping motor, that should help:
http://forums.iboats.com/showthread.php?t=158086
There's a whole bunch of other threads in the FAQ covering carb, ign, etc, at minimum I'd suggest replacing the impeller (check the gear oil and if it's milky also replace the driveshaft oil seal while you're in there), cleaning/gapping the points or installing a "tune-up kit" (new points, condensers, points wick & points cam lube), and removing/cleaning the carb.
Also check the fuel pump screen and, if the fuel pump cover has a cork gasket (screen underneath), replace it with a new gasket. Almost guarantee that the cork will be all dried out and it'll leak like a sieve.
At any rate, once you go thru your basic maintenance items she should give you many years of faithful service.
HTH & Have Fun...........ed