As a pretty new poster, I’ve looked at several sub-forums before thinking this one may be a close enough fit for my question. Have added a few related details so (hopefully!) it shows I’m not just fiddling without a clue.
Early W126, replacing the regulator slides. They come with two wave washers (as per picture), stuck together with manufacturing oil. Have checked all parts in the kit and it’s not just a one-off; all are supplied with a pair. The former parts had been roughly replaced before and only carried a single washer.
I can’t find any information after scouring the web, as to whether the washers are assembled (a.) both together or (b.) one either side of the main plastic part. (This would seem the logical way to me.)

Related note: I did find a really encouraging thread on this forum where a fellow pulled down the regulator power head, it led me to do the same. Now reassembled with fresh grease (lithium base) and cover reattached by 8-32 stainless button head machine screws:

…I chose imperial fasteners because the thread is marginally coarser than a similar metric spec, and going into soft metal it was a detail I valued. The motor’s “Otter” brand current limiter was failed open and has been bypassed with a suitable jump link in the brush holder.