that could be my problem as well. will take a look when i'm home tonight
I've had reos over the past 4 years and since ha e a crap load of old drilled bottle caps from reos mods. As I figured if your bottle is able to easily slide up and down your tube the hole is too large for the tube.
Older caps has smaller drilled holes thst hold tight so your bottle won't move. So I swapped the cap with an older cap and bamb... all good.
I've had this prob before with 1 out of 3 metal reos and I did the cap less mod to fix.
So when the hole is cut too large your bottle will push up when you go to squank her. The tube will seal at the bottom of the bottle as well giving you dry hits and a wobbly bottle in your mod..
Pulling the bottle down to fix the woddle will only fix it till your next feeding.
A fix would be to grab that extra bottle cap you got with your reo and drill a fresh small tube hole with a drill bit. Then prob work your way up to a larger size testing the fit first. It should be really hard to twist the tube threw the hole. Will need to wet it with juice to lube it.
If you mess that up grab the bottle top with hole and drill that out and go capless.