A bit of repair advice please

Flanging_Fred

My much loved old Arion SAD1 analog delay has started giving me a problem. It's got power and passes signal but there's no delay. I took it off my fx board and it was sitting on top of my amp and it got a bit warm and it started working again.  Took it off, let it cool down a bit and after a while the problem came back.

So I'm guessing here that it must have a cracked solder joint some where. I open it up but cant see anything obviously cracked/dry. Is there a good/quick way to find out which part has a dry solder?  Do I need to get the multimeter out and check for continuity across all the components? I have a feeling there must be a smarter way to track it down.