The small part which holds the 2 trigger adjustment screws is black. I think that bit slides, so it coulld show wear marks.
The larger part which holds the trigger blade is a cast alloy (mine had oxidised a bit, so I polished it with Autosol)
Keen but clueless..
Do you mean BK036 on chambers? https://www.gunspares.co.uk/products/24724/TX200SR/
It looks like they have labelled it wrong ('cover plate screw' instead of 'cover plate'), as B1306 is also labelled the same, but the prices are different. If that is the correct part, then for £5 it is probably worth just getting a new one.
I have been experimenting with laser cutting some new washer/shims from nylon (W085 and W086) as I can't find replacements for sale anywhere. They are untested as yet. I tried PTFE first, but they only lasted about 10 shots before deforming enough for the groups to open up. Let me know if you would like some of the nylon ones to try, as I now have about 30 pairs.
The part is similar to the standard TX part except for the back end being cut away underneath and the small plate screwed on. Could you pick up a TX end plug and have it machined? Probably too much expense, but if you just have to have it.
Just discovered that the anti bear trap casing is also aluminium. You learn something new every day.
the back section is made from aluminium. to if its marked or scratched etc. you can strip the old anodizing by using a aluminium etcher like ac115 then have it re anodized. I had a tx in yesterday for re blacking and this had the same problem. if your not sure if its steel or aluminium put a magnet on it. if its aluminium it wont stick