I havent had any complaints about the 12" 1.5 Devastator wand, in fact I have 4 customers that have come back and bought more because they are very happy with the recovery and how maneuverable it is.
So far everyone is very happy with it, I use it 95% of the time over my 14" wand.
I am doing a job his nextThursday due to a referral from the neighbors....I used the 12 1.5 and she was so impressed with how clean and DRY her carpet was.
If I was getting negative feedback from my customers that are buying the 12, I wouldn't sell them anymore, no one has called and said it is a pos, just the opposite.
You could possibly try a hole
glide and see if this would help, you keep saying it is locking down, and that isn't what you want it to do.