Hi!
Many times I have seen complaints about missing or malformed parts. Here's what I have been doing. I raid, or did, vendors at train shows and Model shows for useable parts moles. These are then the subject to the scheduled surgery.
Surgery? Yep, Amputation Mark 1. This gives me a drawer unit full of Zip-Loc bags labeled and containing the most important parts that are hard to duplicate. I Vac them and make a Female set. I turn around and make the copies from these patterns.
Sculpey anyone? Best darned stuff for making those molds with. You can even use them for Slump( Different from Plunge) Molding. The plastic gets heated a little hotter than normal and dropped over a mold and left to cool on it's own. Then like a Vac kit Trimmed to fit the model. This can be done with Female and Male molds.
You don't even have to do this. I tried this trick and almost blew my mind when it worked. Casting - Resin. Did you know you can drip it into a female mold made of plaster of a Fender say, Then pour thin layers rotating the mold To get thin coverage inside and then after four layers and cure time, Break the plaster mold. Viola' pristine part.
DON't Let the lack of customer appreciation get your Goat. Do your own replacements and the Heck with their so called "Customer Service" . I tried doing Vac-Form Canopies and Model Car windows to sell. That turned from Fun to total Hades. Everyone wanted something I didn't have. So make yer own fer you. Help if you can but don't get brave!