The original untouched rear vision mirror from TS79550-0 has an extremely fine "wriggle" finish behind the mirror part. It's hard to tell with the stem. Under a magnifying glass it looks to be fine grain wriggle.
The bracket under the mirror stem that holds the windscreen stay rubber is also fine wriggle finish, like the mirror.
Perhaps the fine grain finish came from the paint setting in the cold, such as British factories in winter. Doubt they bothered with heat drying to obtain a coarser grain.
Whilst a kitchen oven would be fine for the central gauge panel, it might harm the plastic mirror surround. I find the wife's hair dryer is just the ticket for wrinkle work. Mind you her eyes roll skyward, having spent a fortune avoiding them !.
Viv.