Missing brights from the knobs?
Here's a possible solution.. If you can lay your hands on any suitably thin aluminium sheet (any colour or texture will do), you can cut and trim to shape and size to match the missing bright(s).. Next, acquire and assortment of chocolate bars and/or other products which have a thin aluminium foil.. Obviously, look for the ones that most closely match the colour of the missing bright - I might suggest in this case, a wrapper from a bar of "Caramac".. It's a nice golden colour.
Keep the foil as flat and wrinkle free as possible, then spread a thin film of PVA on the reverse side, i.e. the side that isn't going to be on show.. Now, press the aluminium piece(s) you made earlier firmly on to the glued surface of the foil.
Turn the whole thing over and smooth down the foil on to the work piece.. Make sure to get rid of any air bubbles and creases from the foil, and leave to dry.
Once dried, the foil can be cut to shape around the edges of the new bright - a good sharp pair of sewing scissors re ideal for this.. Work slowly and carefully to obtain the best possible neat and tidy finish.
Texturing the surface is not easy, but if all that is required is a matte finish, lay the newly made bright(s), face up, on a hard flat surface.. Next, lay a piece of fine emery paper, abrasive side down, on top of the bright, and gently roll it down with almost any cylindrical object you have to hand - a coffee mug will do.
Just slowly and gently roll the mug (etc) back and forth, checking frequently to see how the golden coloured surface is progressing - it's better to under do, than over do this step.
Once you're satisfied with the result, burnish ever so lightly with a cotton cloth to give a very slight brightness to the newly made bright.
It shouldn't take too long to make new brights this way, but it is well worth make a few practice pieces to begin with, and get a feel for how it goes.
Obviously, the new brights will never exactly match the missing ones, but will be much neater than a plastic knob with a blob of dead and dried glue on show.
Though I no longer have any equipment with home made brights, I used this approach to freshen up a tired looking Rigonda "Party Time" record player, about 1980, and an HMV portable record player that had lost a couple of brights, at about the same time.. I've also refinished several radio knobs this way (transistor portables) and a "Linear" amplifier I once owned, about forty years ago.