I have an upholstery project I would like to take on myself. How can I tell whether the wood frame needs repair or gluing without tearing into it?

The craft of (RE)upholstery is, without a doubt, a key solution to the problem of furniture waste (12 million tons of furniture go to landfills each year in the U.S. alone). Please consider supporting the National Upholstery Association in their efforts to expand professional upholstery education. We need more 'boots on the ground' to do this work. Thank you. (nationalupholsteryassociation.org)