I was surprised to find that I could spin the crank even though the IP was locked with the locking pin.That test may indeed show something that's broken, or it may causesomething to break. I'd be really leery of using the IP to keep the crankfrom turning.
Something's not right. If you had it far enough apart to swap pumps you should have seen the sheared spline (or whatever). Could the timer have come apart internally? -- Jim