abstract: In his seminal 1926 K $\in$ JWKB paper, Kramers modified the centripetal potential of the radial Schrödinger equation to improve agreement of the JWKB with exact solution, and he triggered a sequence of further modifications over the next eight decades. The surprising fact is that most, if not all, of these modified JWKB expansions are Borel summable to the same physical solution.