Nearly always an adjustment in the SS machines. Could be a lose wire on one of the EOS blades. If the flipper has full power (the ball moves fine in normal play), but the flipper drops when the ball hits it - then t will be EOS.
While the flipper button is pressed, and the flipper makes a humming noise, or "chatters" then it could be a worn plunger or mushromed coil stop. The coil stop could also be magnetised.
A simple test.
Start a game and press the "good" flipper button. Push down on the flipper itself. Should be a fair amount of resistance and then a "hum" as you push harder, before it drops, and then returns very quickly to the UP position.
Compare with the "floppy" flipper. If it drops without much resistance, then it should be an EOS problem. Clean and gap the same as the strong flipper and report back. The coil will become WARM if the EOS is not closing, then the coil will hove no power, then the scoil sleeve will melt.
It could also be the diode across the secondary "hold" winding. But I doubt it.
Which machine are we talking about ?
