On Sun, 16 Nov 2014 21:46:48 +0000, mroberds wrote:

... Put your fingernail or a guitar pick in
between the vinyl and the hard plastic and slide it back and forth.

I have dodgy fingernails and no guitar pick, so I use a Bic ball-point pen
cap instead for that sort of job. Could also try toothpick or cocktail
stick...

Mike.