Hi Norm
I would never sell a mower with a bar blade on it either - too many issues hitting things. These quickcut swingback bar systems are a step up from that, but still lousy.
When you say the 3 screws holding the base, do you mean the 3 small blade boss screws? If so, I have personally had that happen to me 2x and seen it another 2.
Perplexing how blades could disappear without a trace. Only thing I can think of is poorly heat treated blades, or the 'grain' flowing across the blade - so it practically sheared at the highest stress point; the bolt.
