Boss HF-2 : rate speed pot issue

[nooneknows]

I have a HF2, I don't use it very much but I've found that in some position its sound is much closer to the one I remember about the CE-1 than my CE-2, so my interest in it has started again.

What bugs me is I feel there's an issue on the range of the rate pot, at least in mine: it goes from really slow to really fast in just a very, very little range of the pot (more or less at 3 o clock), is it just mine or is it a common issue?

Any idea to get a more friendly sweep ? I read a 250KC on the schematics, but the pot are really small, I don't think I can get something with a different taper with those dimensions that easily