@Elmar Riachi and @Mike - All ME-5s get sticking buttons - this can be partly alleviated with some electrical contact cleaner spray.
The footswitch probably just requires some contact cleaner too. If you purchase the Upgrade Set here, you get a copy of the workshop manual included to help with further maintenance etc.!!
@Mike - If you want to include any images or other on the process I can create a page on the site to show others?? Add another comment and include your email (it won't go live until I approve it and thus not show) and I can communicate with you direct then off-site. Thanks for letting us all know!