[sdiy] Piher PC16 warning

[JH.]

> Two warnings regarding the Piher PC16 series of pots.
> 
> Plastic shafts are splined but have 30 teeth. Splined shafts
> usually have 18 teeth. Knobs designed to go on splined shafts
> don't mate with Piher PC16 pots.
> 
> The feel of the wiper on the track spells "cheap". Those pots are
> apparently spec'd for 25k operations. All I can say is that they
> certainly don't feel like it.

These are the worst pots I've ever seen. Everything I've buit with
these went scratchy after a few months.

JH.