how can i release the winding spring for the chime in my hermle wall clock?

Over winding a clock is a myth. If the clock will not chime it is because there is something wrong in the train. The best way to test it is to lift one of the locking levers in the chime train and see if it begins to chime. If not, you will have to find out what is interfering with the power release in the train. Do not try to let down the mainspring with the key as you may brake your fingers. Clock repairmen use a special key to release the power from a spring.

Stevens Clocks
June 2010