If it were me...
https://www.amainhobbies.com/castle...esc-motor-combo-4600kv-cse010-0115-05/p618576
I just noticed - yours has a different transmission on it. That looks almost custom made
How many teeth are on that spur gear? Just curious.
I would grab a replacement.
https://www.amainhobbies.com/team-associated-48p-stealth-spur-gear-81t-asc6693/p43519
For pinions, I would probably grab a few different sizes, just to play around, starting at 14t and going to 18t. 18t will have that buggy ripping with that motor, but may make it run hot. Probably not though as the B3 weighs next to nothing. Depends on the battery you use, and how well the bearings are (which I would definitely replace). Fast Eddy Bearings probably has a new set. Yup...
https://www.fasteddybearings.com/team-associated-b3-factory-team-sealed-bearing-kit/
Robinson Racing makes the best pinion gears. You can grab one of the Six Packs here...
http://www.robinsonracing.com/catalog/one_eight_inch_bore_pinions.html
For a servo... Reedy is Associated brand, and they are fine. Especially if you're not driving it that much.
https://www.amainhobbies.com/reedy-...etal-gear-servo-high-voltage-asc27110/p671903
But I can't tell by the pics... does yours have all the servo mounting hardware and the bellcrank?
You might want to grab a screw set too
https://www.amainhobbies.com/rc-scr...qHxQChHU0Ig9Sz3kSvVKBcJaNrZzC4EhoCWF4QAvD_BwE