They are lots easier to fit with a special tool (I made one from a wood handle and a wire coat hanger) Basically you bend the wire in the shape of an arrow head,the arrow head is put in the groove and is wide enough to force it ope as you push it along.You feed the new strip through the centre part of the arrow so that it goes in where the rubber is being pushed apart. Plenty of soapy water helps. Alternatively you can use a screwdriver with the blade wide enough to open the rubber and push in the trim a bit at a time.
Most windscreen fitting firms will have the proper tool or,I have seen them for sale (I think from Woolies).

Yes.it's also easier to remove and replace on a warm day when the rubber and filler strip are more flexible.
Some of the filler strips will crack if bent at a very sharp angle.

Thanks for all your help, have ordered new inserts, feel confident about fitting now. Thanks again.

The Reps and Maintenance section appears to be monopolised by Taxis no longer being used for their purpose, therefore non taxi drivers like me can get help, but does this annoy the members in the cab trade, if so I'll try not to post, but you're all so helpful.

Yes annoys the feck out of me,sell it and get a car

Got a car, no contest if I have to sell one. No car has ever made me smile, the way I do in my cab.

Itll wear off,maybe if you drove 12 hours in it the love affair would end !