Hi, Mike.

Chain must be oriented correctly relative to bar to cut. Rails on
bar can be worn unevenly, as can chain side-straps, so that chain is
misaligned to either side. Easy way to check bar is to place 6" or
longer straight-edge on the rails, then see how square that is to the
bar face.

I've trued up a few bars with a bench grinder, after which they cut
"like new."

The chain straps you can give a quick visual, or caliper-measurement.
If worn close to pivot pin, the chain is unsafe anyhow, and should be
tossed.

Generally these problems are caused by hitting a rock or other nasty
on one side of the chain, and continuing to run the saw. This presses
the chain more firmly against the bar under the dull cutter(s), mainly
wearing the bar. Yet another reason to check and sharpen the chain
with
each refueling. DAMHIKT

HTH,
John

Michael wrote:
I have a 009 Stihl saw, 12 or 14 inch blade. It cuts find
to about an inch and a half, but then it acts like the chain
is dull or something. Cutting the rest of the way through a
limb takes a lot of doing.

I notice that the bar at the bottom is not in good shape. It's
worn down and spread out a little. So I turned the bar over
to the good side, and that didn't help.

The saw is 20 years old. The bar is probably 10.

Thanks,

Mike