2 spd pump motor won't start on high but will start on low, timer-switched to high

[winegum]

Hi, found some related threads on this but nothing definitive, I have a 1 1/2 year old Jandy Stealth SHPF 1.5, 2 speed main pool pump (delivered from INYO Dec 2015) ran fine until the other day I tried to start it on high for backwash and it tripped out (buzzed then overload tripped it off for a while). After it cooled off and the thermal overload reset, it would start on low, then I was able to switch into high speed, ran all day. I have an Intermatic T106 2 spd timer (jumpered for low/high) wired into main Intermatic timer. Configuration has been working fine since installation Dec 2015. I initially suspected the start capacitor because once started on low, I can flip the timer into high and it will run all day no issue. But try to start from full stop to high it trips offs. Another web forum post I read had same issue and they replaced the capacitors without resolution but still has me thinking either start capacitor is weak or could it be a centrifugal switch issue?

 

[winegum]

Update: I found similar capacitor used in another motor I had for the waterfall which we seldom run. Swapped out the capacitor out from the waterfall pump into the main (problem) pump and it now I can start it from stopped to high. The problem capacitor is rated 25uf 440Vac while the swapped capacitor is rated 25uf 370vac. It is a 220volt system but there is a reason why the manufacturer put a higher VAC capacitor. I don't have a clue as to whether it s going to be a problem down the road. Need some theory here i.e. in what circumstance would the motor pull enough amps to exceed the 370vac max limit?