Just out of curiousity have you ckecked the valve lash yet? This is another area where there is more clearance when cold than when hot. Not all the valves wear the same, so there could be a loose one on the left side. As for the tensioner, the aftermarket ones used a bolt, not a srew, and a plate that bolts right up in place of the stock tensioner. By tightening the bolt, you are putting more pressure on the rear guide, thereby taking up the slack in the chain. With that many miles, I think I'd at least check the upper guide and set the valves just to be sure. Also, the newer Concourse tensioners don't have the rounded tip anymore, and they are automatic tensioners, which makes it next to impossible to overtension the chain. Keep in mind that these engines had "soft" intake valves that would often pound themselves right through the seats, and most new bike owners assume that if the bike is running ok, theres no need to take it in for that expensive service that the manual calls for. So checking the valve clearance is a good idea unless you know for sure it's been done recently. And while you're in there, checking the upper guide gor wear won't take much longer. You can also measure the chain links to be sure your chain isn't out of spec. Hope all this helps to some degree!
Later,
SS