I would also be inclined to check the turntable before condemning every Pickering stylus out there. Another question: does this particular KLH 11 actually have the AT6 turntable? Only the early ones did. Later ones weren't AT6 but a turntable made for KLH by Garrard designed to specifically use that particular Pickering cartridge.
....and nothing BUT
The few of us on here that own one of those Garrard 3000 series "custom made for" changers have no choice but to use the existing Pickering cartridge body.
As long as it's ok, it can be fitted with an N400 (used in the 400.v3) stylus for some "punch"
Set the tracking for 4 - 4.5 grams, and you're good to go.