Lazy pop bumpers

[skywalker]

Hey all, working on this machine MM & noticed the pops seem lazy/weak, once ball is launched then travels down either 1 of the 2 lanes into the pops doesn't seem to be much ball action, All the pops work ok, looks to be recently over hauled with new parts, contact gap is ok, ball hits pop may deflect onto another on pop but no real power/action just dribbles out with no energy, All the shirts look ok with good spring compression & rebound, Bumper ring assembly travel works ok, coils are to spec, The only adjustment i can make now which is minimal is to have the shirt plunger seating into the spoon with zero clearance,
 Any input would be helpful

[Retropin]

Make sure the pull rods aren't fouling the playfield... any slight bend in them or put back in slightly off centre and they'll rub the PF on the way down making them appear sluggish

[studley67]

check for cold solder joints

[skywalker]

Thanks for the extra info