I have an mp 40 I just got but the suction on it isn't strong, I seen there's a mount for the cord to hold it up but I don't have that, should it be able to stand up without that cord holder?
You're going to want to get the piece to attach the cord to the glass. You can get them at lowes or Home Depot in the electrical section. How thick is the glass and are you using the correct spacer? They are pretty strong when set up correctly.
Well that's strange .like .kschweer said grab some of those cord holders from the hardware store. Maybe they're required to hold in place e. Honestly I didn't try them without being attached.