Will make it worse, and a 12mm eyepiece is rather short for a finder - the field of view will be small and the magnification too high - you really want one around 20-26mm.
There are some cheap ones around e.g..
https://www.bhphotovideo.com/c/produ...der_scope.html
http://www.apm-telescopes.de/en/opti...ect-image.html
APM have them with the right matching eyepiece and illuminated reticle, which is what I'd buy to make sure it all fits correctly.
You could also replace it with something like the little skywatcher "heritage" 130mm newtonian scopes - pull the OTA off and put that on your scope, and toss the mount.