There is probably a stop plate on the outside of the cylinder which houses the spring.
And a stop pin on the pulley cage.
You'll be able to identify these pieces by twisting the derailleur and see what prevents the cage from moving any further.
The pin should be on the other side of the plate.
Easy job if stop pin is removable otherwise disassembly may be needed.
@dmczone started
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There is probably a stop plate on the outside of the cylinder which houses the spring.
And a stop pin on the pulley cage.
You'll be able to identify these pieces by twisting the derailleur and see what prevents the cage from moving any further.
The pin should be on the other side of the plate.
Easy job if stop pin is removable otherwise disassembly may be needed.