Damp patch on conservatory wall

dancelikeamonkey

Hi all, looking for a bit of advice.

I moved into my new home last week, and noticed that there was a damp stain on the interior wall of my brick built conservatory where it meets the roof. I've been up on the ladder, and it's below the point where the guttering from the garage roof meets the conservatory roof.

A repair has been made because some of the wood from the frame has been cut away and replaced and a thin layer of bitumen type stuff has been painted in the gutter approximately above where the problem appears.

Anyhoo... that the backstory, my question is, is there anyway of finding out if a problem still exists (I have no way of contacting the sellers to find out what repairs were done or if a temporary bodge was applied)?

Is it worth sealing the stain then over painting it to see if it comes back, or will that just result in the problem possibly worsening but me not being able to see it?

Anyone aware of any other ways of finding out if water is still penetrating the wall somehow?

Thanks in advance (and sorry for the long post)