The repairman that came to take a look at Fix-It Felix Jr. wasn’t actually a repairman at all, but an avid collector of old arcade games. His video game obsession of choice: Fix-It Felix Jr. (Hence his Felix-looking attire).
Posing as a repairman, he takes one look at arcade games, claims there’s nothing more he can do and buys the game off the owner on the cheap.
When he came to pick up Fix-It Felix Jr. only to have Mr. Litwak point out that the game was fine, he claimed it was a malfunction, that the game would start acting up again shortly, and tried to make several offers on it before Mr. Litwak turned him away.
(BONUS HEADCANON: The fake repairman holds a long grudge against Mr. Litwak and his arcade, until months/years later, he finally cracks, breaks into the arcade, and steals the Fix-It Felix Jr. game, becoming the sequel’s new villain.)