A 2002 Ridemonkey forum thread includes multiple posters confirming that Loose Screws and Third Hand were run by the same people. One user notes that both businesses were located in the same town. They also talked about a combined catalog titled The Third Hand/Loose Screws Catalog Vintage Bicycle Tools & Parts 19992000, which further supports the connection between the two.
Loose Screws started to go out of business in 2012 and went out completely in 2014; Third Hand went out of business between 2000 to 2003.