Fusion /= strength
perhaps my amateur status will seep through here...
IF these are points of stress where the cracking is taking place, simply adding welds wouldn't seam (sic) to be the solution? It would only add to the rigidity / hardness in the area, no?
I do see (more lately?) some are adding plates to spread the energy over a wider area, this makes sense, IF the ductility remains similar.
Any metallurgists on here?
More simply, the original part failures are known. How about failures in these weld 'reinforced' crossmembers? Any history from those performed around this time of TT tech note publication or later fixes?
(I've a plan to swap out original for a reinforced unit. But may need to reconsider HOW the reinforced unit was prepped.)