hi,
we are doing BLW, a suggestiong, how about mixing the food that you chop up in with a bit of mash potato... plong the 'mush in front of him and let him grab amounts of this food.
once he masters feeding himself this, then move onto larger chunks of food. this might help.

MJ still has no teeth but manages to chew things.
I was going to ask the same question as you NJD
The other thing... how is his sitting balance? and where do you feed him? is he completly upright? i know that if MJ is slightly reclined like in a push chair or similar she is more likely to cough and gag.

how hard is the food that you are giving him? could you make things more sloppy... like really soft carrots and broccoli... the broccoli that i gave MJ to start with almost falls apart when she grabbed it

HTH