Stang,
take it back apart, where the female wire connecters are see if they are wiggly ( move around easy ) or if they are snug... I found on my old CH analog sticks ( had 2 Fitersticks, a combat stick, and FX fiter Stick ) that the spikes came from the wires not being crimped down tight enough.once I crimped them down with pliers ( linemen pliers ) I had excellent response and hardly any spikes
just a guess.
I only have my old janes combat stick left and the CH hotas fiterstick/throttle/pedals gave away or traded the rest to squaddies...... mine is dated 1996 and is still working fine.. the other I gave to a squaddie only replaced 1 or 2 pots in it........
good luck!