413 Timing Question

[69Adventurer]

Am I understanding this correctly? My timing chain is bad?
When I have a timing light on the balancer at an idle I can read the mark clearly
cause it's in the same range (within 2 degrees)
But when I rev up to 2500-3000 the mark is all over the place (bounces 30-40 degrees)
and I can't get an accurate reading? I was told my timing chain is bad? is this correct?

[hoffy09]

Remove your distributor cap. Make sure your ignition is off or your battery is unhooked. Using a socket and breaker bar (or just using your hands if your compression is down) rock the crank pulley back and forth while watching the rotor. There should be almost no noticeable lag or play. The rotor should move exactly the same as you move the crank pulley. If you can rotate the crank pulley back and forth a few degrees and the rotor lags, your chain is sloppy and probably time for a new one. Good luck.