Sealing Pex Radiant Tubing with a Sealant??

I've had a chronic small leak (apparent by a pressure loss) in the 7/8" pex tubing that I used for a radiant heating system. The 700+ ft. of tubing is inaccessible from the top under a hardwood floor and 3/4" plywood. The tubing is inaccessible from below as it is installed over 3/4" plywood which is over insulated 2x12s which is above an older concrete slab that was formerly a patio. The pex was purchased from The Radiant Floor Company in Vermont and was pressure tested before covering, though after one nick in the pex was repaired using barbed couplings secured by hose clamps. Radiant has not been helpful in solving this situation. I've tried "Silver King" boiler additive with no success (the manufacturer said it would work with pex). Is anyone aware of a product that would have the ability to seal this leak and hold it within the operating temp (up to 200 deg) and pressure range (12 to 15 or 16 psi) of this system.

The only way I know of to permanently fix that, is to re-do the repair and use a high quality clamp made for the system....

boiler seal will not work with pex. Pex tubing is too slippery for the chemical to bond to. Barb couplings and hose clamps is a hack repair also. Pex needs to be repaired using the proper fittings. Who installed this and why was it not pressure tested before it was covered up?

Some of these radiant/hydronic install questions always have me wondering why they are not talking to the plumber (hopefully it was a plumber!) who they were working with.

Betcha it was a DIY install.