Corroded electric contact - Flash fl-36r

Good afternoon. I own a fl-36r flash, and the last time I used was at new year's eve. Two weeks ago, I opened the battery lid and found out that one AA rechargeable leaked, corroding an electric contact.

Corroded electric contact

Although it still works fine, I would like to know what can I do:

- Can I improve it somehow?

- Is it worth to send it to repair (probably not, I know...)

I ask it because of the reselling value. Can it get worse over time or should I just relax?