The red twinkle light works, the yellow twinkle works, and the blue seldom works. If you take the blue lens off and push the bulb a little it works with regular consistency. Sometimes all the twinkle lights will quit and then restart if you wrist rock the toy some (give it a shake).
Maybe take it apart and clean contacts would help. The item "Remco Science Fiction Child's Space 1999 Stun Gun Vintage Toy with Original Box" is in sale since Friday, January 31, 2020. This item is in the category "Toys & Hobbies\Robots, Monsters & Space Toys\Space Toys\1970-Now". The seller is "auctionexchangeusa" and is located in Nokomis, Florida.
This item can be shipped worldwide.