FAB Echo problem ?

[MartyMart]

I did the mod to the fab echo recently, adding a delay time control pot.
What's happening now, is that when set above "slap echo" - which was it's original
role, It often but not always takes a minute to settle down and stop modulating !
ie- longer delay setings, such as 200msec and above , cause modulation to happen, which
of course sends the tuning of the delay signal into wierdness and doesn't sound great ??
What do I need to look at as far as stabilizing this ?
Is it just that my tiny 100k pot is too much of a value change and I need a 22k or so ?
Problem is that I dont have any pots of that value so small ( 12mm )

MM,

[MartyMart]

BUMPITY  !!

[Meanderthal]

 Maybe a resistor across the lugs?

[MartyMart]

Maybe a resistor across the lugs?

Now why didn't that one slap me in the head ! DUH !
100k across 3&1 = 50k pot .....could just be that and the pot is v-small so quite
sensitive to any tiny movement.
Ta