From painful experience, at 14 degrees with a stretched chain, and a weak tensioner, you have either jumped or are about to.
You obviously need to replace the upper rails. The folklore is that the lower ones are bathed in oil and a supposed to be good for more miles.
I would definitely try to get the tensioner to pressurize and hold the chain tight while cranking the engine before starting. And then check the alignment of the cam and crank marks with the chain tight.
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe