If you need to service the pump, replace the pump internal filter or check the pump vanes on the 508FS or 686 machines, you will first need to gain access the interior of your machine. For instructions on how to access the interior of the 508FS or 686 please see related articles.
The video link below will show you how to service/clean the vacuum pump fitted to the 508FS (Becker VT4.10) but similar procedure applies to the pump on the 686 machine.