Rick speaks the truth. If you use the plastic-coated springs, plan on replacing them at most every two years. And if your springs are already peeling, discard and replace. You likely won't get all the plastic, and the bits that you miss will get up into your valves and cause them to stick.
Voice of experience.
David Bjornstad
1923 Conn New Wonder 86I, Bach 6 1/2 AL
2018 Wessex EP100 Dolce, Denis Wick 4ABL
2013 Jinbao JBEP-1111L, Denis Wick 4AM
2015 Jinbao JBBR-1240, Denis Wick clone mouthpiece of unknown designation
Cullman (AL) Community Band (Euph Section Leader)
Brass Band of Huntsville (2nd Bari)