Parktronic on a CLK

[WOO5IE]

Hi all,

I am normally on one of the other marques on PH , but I have an issue with my Parktronic on a 2001 CLK Cab being mainly in alarm. Sometimes it works fine but soon after it will be back in alarm.
I suspect one of the sensors on the front being intermiitent.

How do these come off/out, are they just a push fit and some sort of sucker to get them out.

Any advice

Thanks