MF, I think the decks are even thinner than Victa's - Masport don't say how thick the deck is on the 18 inch in the brochure, but the 19in is 1.6mm steel. All they say is the 18in is made of 'durable steel'.
Pair thin steel with possibly poor heat treatments (too much hardness and not enough toughness) in the chinese factory and that could be the causes of brittle failure.
Not sure how thick the Victa decks are, but I am quite sure a victa with a 450 briggs is heavier than a masport with a 450 (I try to avoid picking up mowers on my own)
But then you have a bigger blade carrier causing +400ish grams over the masport quickcut.
I do know a masport of this age with a quickcut bar will lift off its front wheels once the catcher is full, a victa wont.
Norm's solution of Talon bases for PT seem to be the best alternative as they are thick and have less rust traps
