Hi, I have a problem with an older LawnBoy, and it will be a few days until I can take it anywhere for service, so I thought I would ask for some objective advice here first.

It's a LawnBoy model 4600, a 20-inch, aluminum-deck, dedicated rear bagger that I bought in 1984 new.

My yard is on a slope (front is 30 degrees; back is 20). I cut across the slope. And the mower is making a lot of smoke and running at a noticeable reduction in rpm while on the slope. It actually smokes more when the air filter is on the uphill side than on the reverse pass where it's on the downhill side.

On flat surfaces like the garage or patio, it runs fine--no smoking or rpm problems.

More background: This summer I started using Echo two-cycle oil because it was easier to measure out smaller quantities and mix one gallon of gas at a time (I have a very small yard). First gallon of gas-oil mix (plus Stabil) was fine. About four or five weeks later, I mixed a second gallon, and this was when the smoking started. I got fresh gas and went back to LawnBoy oil, but this didn't make a difference.

I also changed the spark plug, but this hasn't made a difference either.

I like this mower because it's lightweight compared to new models, but I also don't want to invest too much in keeping it going.

Thanks for any thoughts you might have.