Hi MF, I think it would be difficult to cut the hole bigger, easy if you had a plasma cutter, very hard without. I don't think the thicker base is the cause they rust less quickly, I think Victa was probably putting a better paint/rust protection on the underside, and I think the Chinese were probably only treating them with coloured water.What I do with the ones I fix, is coat the inner left hand side with fish oil so this hopefully will give the bases a chance of surviving another 10/15 years
