The metal ‘technically’ isn’t there to support the flow frames. The support is found where they ‘hang’ off the rebate in the super box. Take the key access hatch off and see if the flow supers are seated properly.
Next, check that the fore and aft movement of the flow super is on. There’s an adjustment screw at the back of the flow super to limit play of the bottom of the flow super so that it sits just on the metal strip. If there is play, a gap can develop. See this thread:
Aim is to minimise gap highlighted here:
