How To Ensure Flatness of Negative in Carrier

I use a Vivitar V1 with dioptic light source and it's unique light pipe system. No heat transfer whatsoever. Glassless neg carriers - no popping!

It was totally by chance that I ended up with this enlarger, but I am very pleased I did!

http://www.jollinger.com/photo/enlargers/vivitar.html

DF said:

I'm not doing anything larger than 8"X10" - the image is actually 6"X9".

Click to expand...

Honestly, I really don't think you should have anything to worry about. I'm really surprised you are seeing problems. Are you sure source of your problems are film flatness and poping? Is it possible your focusing stage is drifting? Or parallelism is way off? Do you actually see problems on your print? Or is it only visible (barely) with grain magnifier?

If you want to use glass type, there's nothing wrong with that. I'm just not sure if it will solve your actual problem.