I went into the shop on Friday to find a white plastic cap about 2cm in diameter on the ground. Before I throw it in the scrap bin, I tried to find out where it could come from. Here my finding

One of the Vac-Sys screw went lose pop out the cap and was about to fall from the base. The Vac-Sys has been used for about 5hrs max. The reason for the screw to get lose is probably about vibration.
Lesson learned #1: Check both screws before and after each use
![Smile [smile]](http://festoolownersgroup.com/Smileys/default/smile.gif)
A good friend of mine borrowed the RO 90 to sand a few doors. He was using the Delta pad and when I removed the pad to put back the circular one I found this.

And this is how it should look
![Big Grin [big grin]](http://festoolownersgroup.com/Smileys/default/biggrin.gif)

Lesson learned #2: Clean residue regularly, not only when you switch pads.