I am using gel bond film for the comet assay rather than agarose coated slides, but am struggling when it comes to the elctropheresis as I can't be certain that the film remains straight and isn't moving around in the tank.
You've probably figured this out since I see this post is from May, I'm new to research gate...
I have had the same problem. I have experimented with this and found that by putting a drop of glycerin on the underside of the slide and laying the slides down in a dry chamber then slowly adding your electophoresis media helped out... some would still move but it really helped.
Please have a look at attached image. This one is for 96 samples.You have to manually design the size based on the length of Film you require. You can easily make hole in the film using hole puncher. Once the size of the film is adjusted to holder, it gets fixed easily. You can take out the film once you have fixed the film. Hope this of help.