When restoring wooden boats I mixed 2 part epoxy and sawdust from a like-colored wood to make a paste, works really well!

I have not used that flavor of plastic wood but i have used that brand.
I found it hard to sand and it shows when you stain or polyurethane it. I would do a test on something else to see how it finishes.

You could try the epoxy and saw dust method.
You can also try the plastic wood but jut try them on scrap before you commit to that piece.
I am sorry to say, when i have run into deteriorated pieces like that, i just make them using the original as a template.
Examples: I remade the trim on my 1956 crossfire and made new legs for my 1959 Bally monarch shuffle bowler.
I am sure there is something that will dress up that piece but pretest. Once you commit , if you are unhappy, you will be forced to get another one.

I've found the only way to get deep a scratched out of wood is to completely sand out the defect. I was never happy with the results from using any kind of filler and stain. It will take a lot of time to do it, but believe me you are going to spend a LOT more time trying to correct when you want to try another material.

I would try what others have suggested. If these efforts fail try asking people in this forum if they have an extra lockdown bar. Also see if one of the Pinball Resource replicas matches yours.
https://pinside.com/pinball/forum/topic/the-em-seeking-parts-thread

The pc looks a lot better just sanded,I wouldn't use the epoxy/dust. Just coating the wood with 5 to 1 epoxy would look really nice and protect it. The scratches/gouges are not deep enough to warrant putty, and even though it is made from dust from the same wood it will dry slightly darker.
I use West System but it is pricy. Good news if you invest in a quart/pint kit with pumps it doesn't go bad.

Nothing wrong with a little character here and there. Sanding and finishing would be all I'd do.

Unfortunately no. Fiberglass resin is cheaper but will look like crap using sawdust as a filler.

Easier than resin is to mix sawdust in with wood glue. I believe I have done this with Titebond (it has been awhile), but you'll have to see if the glue will take stain evenly before you commit to using it. Try your mix on a scrap piece of wood to see how it takes a finish. If you pack a lot of sawdust into the mix you may never see the glue on a small repair anyway.