Z height touch plate problem

Hi all. Apologies first, if this has been already been posted in the past, but i had started to get some failure when using the Sienci touch plate while preparing to surface a board. I had looked at these forums and people were saying that one cause is oxidization on the aluminum touch plate which mine did not have. I then replaced the touch plate magnet with a crocodile clip as I had noticed in the past you did not always get a good connection when attaching it to the nut on the tool head of the router. So now I always attach it to the bit in the router. But this did not cure my problem. So when I removed the surfacing bit I noticed that there was a small build up of crud on the cutting surfaces. I gave it a clean with a stiff nylon brush and denatured alcohol put it back in the router, went through the touch plate routine again and it all worked flawlessly.