yaris 2004 model door lock failure

[borquee]

Hi,
New here... hello!

So, doorlock on the passenger side is not locking when it's warm outside (in winter it works fine). It can lock with a key (from outside) but not with keyfob or button from inside (driver side button).

Spring is here and my door is not locking again. Service asked for about 200 Euros (before looking into it) ... sounds too much for any repair.

I am willing to try to fixit myself... Anything I should worry about?

Thanks,
Bob