Does your 964/993 spoiler sound like a coffee grinder?  It's common knowledge that the bearing in the spoiler gearbox is not sealed and eventually goes rusty, causing the noise.

The common 'fix' is to cut open the spoiler gearbox case, replace the bearing and glue it back together.   Unfortunately, the glue nearly always fails whether it is super glue or epoxy. See pictures for a glued gearbox that has split after a few weeks of use.

This kit has a re-engineered cover that does not require glueing, making the gearbox serviceable in the future. A new bearing is included.