As someone who has had to replace the glass 3 times now, one vandal smashed and two stolen when on hols in Biscarosse France. The plastic mount for the glass to clip onto sometime does not hold and the glass shakes.
1st thing to try is, with a cloth to avoid them sticky fingers, press the centre of the glass and see if anything clicks into place, if not try pressing up and down etc as it clips in 4 points. If that no good follow the others and shove something under to dampen the shake.
And if you go on hols to Biscarosse watch out for bum end of the surfer market that will pinch bits of your T4 while you are on the beach. Rasp: