I'd suggest the first place you go is where you bought the furniture. If you don't know the mfgr., perhaps the Customer SErvice people can help. They SHOULD know who sold it to them, especially if can give them a 'product number'. (If you have any old receipts or brochures, bring them w/you ...)
The next method is to see if you can determine the mfgr some other way. From there, ctc the mfgr. and see if there's a way to get parts.
And lastly, you may find what you want at Home Depot, Lowe's, Sears, and/or the like. The only problem is you might find that the furniture parts are slightly LARGER or smaller than what you have and, hence, won't get a good fit. Bring a part w/you to see how it goes. Those stores should have the 'T' and 'Elbows' and so on.
Other than that, I'm at a loss. My best to ya and hope this helps.
Jay J -Moderator
PS: Which Tri-State-Area? PA-NJ-DE? My mind wonders how many 'areas' in this country has a 'Tri-state Area'. Welcome, nonetheless!