The plastic caps you refer to , I usually call the snarewire hanger. I suppose snarewire yoke might do as well. It looks like your wires are a conventional set, with black plastic ends or a broken black Trixon set, missing the sleeve at the end and have been attached to the hanger with snare cord( nylon stuff). While this will work and a lot of Trixon drums are adapted this way, the original settup had the wires seating right into the hanger and being attached with 3cm. pins, which went through the ends of the hanger into the above mentioned sleeve.
Trixon had 6 versions of that hanger , only using the plastic ones for one year(1967). Any of the cast or stamped metal versions function in an identical way and are a more permanent replacement for the plastic ones, which tended to crack.
I might have an extra set of snare hangers----I presume you have the adjusting knobs etc and I can make you up a set or 2 of 26 strand wires.They will have authentic Trixon ends, so you can properly attach them to the hangers and contemporary wires in them.They would essentially be brand new custom made wires. All I can say, about the missing mechanism is-----keep looking but bear in mind what I said before, that one of those for a 14" bottomed drum is much more likely to be found and can be retrofitted to work on the Telstar-----if you're a bit handy. All you have to do is remove and shorten the connecting link and since you already have one , you have a template.