ABOUT FOUR years ago, Russell Rowe decided to enroll in an adult education course in lawn mower repair at a local college. "I wasn't doing anything at the time, so I took the mower out there and got it all fixed up. At $25 for the course, that was cheap."

Today Rowe spends most of his time in the basement of the Apex hardware store in the Spring Valley area of Northwest Washington fixing other people's lawn mowers. There's a whole pack of grass eating machines gathered in the rear of his workshop, awaiting his attentions.

The beginning of the mowing season is heralded by bearers of mowers that won't start. Usually, he says, the mowers don't turn over because they have been sitting in the garage all winter and the owner hasn't thought to change the gasoline in them. Gas, even at today's prices gets stale.

So he cleans them up, gets them started again and sends the owner merrily on his lawn-clipping way. "Then they scream like hell when they come back with the same problem, because they poured more of the same gas in it, and I charge them again for cleaning it."

Rowe normally charges $18.50, plus parts, for a routine maintenance overhaul. More sophisticated repairs cost more and require special tools. But the average owner can save some expense by performing basic mower care himself.

First, get rid of old gasoline and change the oil. Replace the spark plug and check the air filter. Air filters are often made out of a sponge material that eventually deteriorates and sends bits of sponge down into the carburetor. Lubricate moving parts.

You will see that your blade needs sharpening if you can't tell where you have mowed and where you haven't. A dull blade will leave the tops of the grass with ragged edges that can turn brown.

There are many shops listed in the Yellow Pages under lawn mower repair that will sharpen a dull blade. Some give two prices (under $5, usually) for a blade removed or not. Don't be surprised if you find your blade under the mower. The bolt is tightened withmore than 100 pounds of torque and secured with lock washers. CAPTION: Picture, Russell Rowe repairing a mower. By Gerald Martineau - The Washington Post