A valve should never, ever leak...the problem should be that as you get fuller the valve gets tighter. So yes, there is a problem (you know that already).
The hitting the side or the wall and having the end 'buckle' is not new to me...it happened a lot when my pouch slipped (no, it wasn't the valve, the whole pouch fell off of the wall multiple times) so that the valve was higher up with the pouch down lower and the whole thing led to impossible angles for intubation.
Yes, once it seems to have buckled you can never "unbuckle it "...mine did it constantly. I eventually had to put a guidewire inside my stoma/valve so that I could follow it with the cath when needed. I covered it with boondoggle so as not to slice my valve with the wire (you need to tape it down so that you don't lose it)...But you do not sound like you are there yet.
In your shoes I would have an opacification done...contrast study in other words...And have them first drip a few drops of the Opac into the valve to see how it looks, then into the pouch, then have them take some shots with you on your side, both right and left, standing and sitting...and finally 1/2 empty...it was the only way that they could get a clear picture of where my pouch was.
It is often not the valve itself but something surrounding it...if the pouch is down (it can happen even 20yrs later) then it pulls on the valve when the pouch gets full and pops it open after a certain 'weight' (read: fullness) and can cause leaks.
It could also be a peristomal hernia that leaves your valve unsupported and can lead to twists of worse.
The good news is if it is not the valve itself but the supporting structure then it is an 'easy' fix...And can be done laparoscopically...without opening up the pouch itself.
The important thing is not to wait too long to have it diagnosis because a fallen pouch can lead to scar tissue on the organs that it is touching and a hernia can only get bigger.
For now, do not go too long without intubating...try the bullet tip tube and baby your valve.
Hope that it is nothing serious.