If so, you can test each unit separately, as it seems obvious that the first floor leak would be from the second floor, but water is a tricky situation.For the roof, I would certainly get several groups out to let them diagnose the issue and bid the resolution.  

The staff expressed great frustration with the system because they could not easily diagnose if the problem was with the meter or the electronic transmission system.

They charge $400 to diagnose a check engine light!

The easiest thing to do is have a plumber open the ceiling beneath you to diagnose.

I have only required service once and just hired the local appliance repair guy who came and diagnosed it and ordered the part and had it fixed in about 5 days.

As a mechanic, it's why I am one of the best at diagnosing.

I have been both formally diagnosed and medicated in the past for paranoia, and I feel I'M BARELY PARANOID ENOUGH for real estate.

I think I'll let WebMD diagnose it."

My medical degree to diagnose my illness being due to mold came from a Cherios box- it was on the back of the box I just cut it out and pinned it to the wall."

HVAC repairs today are typically pretty easy to diagnose.