Do you have other rubber caps to experiment with? In my experience they affect how much force is needed to move the pointer around (my favourite is the concave with the rim as you pull the rim rather than push the side of the dome...I've probably explained that badly but it's worth trying some different caps if you haven't already).

no, i didn't even know the caps were swappable out! i'll experiment with a concave cap if i can (work laptop, so i'd have to get it okayed first)