I am not hopeful that the replacements will be made available, due in part to the MTH line being acquired by a new company. Here is why…
I collect 1/72 diecast aircraft models. I had purchased a particular Corgi Lancaster Bomber when the version I wanted was released. I had owned it for about four years before it started to disintegrate. It was a $160 model and the zinc pest problem was present in a few versions of the plane, but others were okay…much like the JLC GG1 with zinc rot truck frames.
Sometime during the past four years, Corgi was purchased by Hornby, a British Model railroad maker. I emailed Corgi, only to be told that the new owner(Hornby) was not liable nor would replace any defective planes sold before their takeover of Corgi.
I would be pleasantly surprised if the new MTH does in fact provide replacement shells as I do own one and it has numerous cracks and paint issues due to the zinc pest…
Tom