Vox V847 overhaul, which footswitch pad?

[jball85]

Does anyone have a V847 (made in USA) that they could take a look at and let me know what kind of pad, underneath the treadle, is used to press/engage  the footswitch? Mine has a white felt like pad about 2-3 mm thick and maybe 1 inch in diameter. I also have a black rubber pad roughly the same size stored with my spare wah parts. I'm trying to figure out which was the stock pad.