Swapped out my rear plain window for a defrost model. Now for the life of me, I cant get more than an inch of the plastic lock back in. Is there a trick?

Buy the proper tool the strip goes through the opening in the tool as you push it in...


Use new lock strip if yours is old & hard. Use some white lithium grease in the channel. You'll be amazed how quickly it will slide in.

I found using a heatgun to warm both the insert and the gasket helps a lot. Just heat about 6 to 8 inches at a time, and using the insert tool, slowly work your way around the window.

I have also had good results when I didn't have the insert tool available with just the heatgun and a plastic scrapper to help fit the insert. Just put one side of the insert (top or bottom edge) into the gasket and use the plastic scraper to lift the other side of the gasket while you use your thumb to press the insert into the gasket. Once you get the first few inches started is really pretty easy. Be careful with the heat gun so you don't melt the insert, a hair dryer may work just as well and might be less likely to melt anything!

I asked a similar question a couple of months ago. I bought a generic insert tool for locking strips off eBay and used it with a generous amount of dishsoap and got it in in about 15 minutes.

you can buy the tool from your local glass shop

Like Minmad said, new lock strip works best. Old lockstrip can be made pliable but putting it in a bucket of hot (near boiling) water for a few minutes before installing. Use a generous amount of dish soap in the channel, and it should slip right in. Then rinse it all down with hot water again to get rid of the soap!