Well done on the work you have done so far on saving another Telequipment scope from the scrap heap.
It was me who was offering D75/D83 parts for sale. The only knob I have left is the smaller A timebase knob. The cost is £2.00+p&p. I have no idea what the postage cost will be but I can find out for you. If you buy it I will include the remains of a B timebase knob as seen here.
https://www.vintage-radio.net/forum/...d.php?t=135544 Perhaps you can fabricate something from it.
The collar in your second picture is actually an integral part of a Telequipment knob. The plastic parts have broken off it.
Al