That is a tuff question, in all honesty I dont know how I could help a mate in that position. Im not even sure I would know they were having trouble, not something I have ever realy talked about with my mates.
Could maybe try and get them to open up on what the issue was with the business over a few beers, maybe time to pack it up and do something different for a while?

But in your possition I would definetly invite myself over for a visit and just happen to have a trailer load of wood I needed to rid of attached to the car