Mechanical advance bad?

[BlackStar]

How can you tell if the mechanical advance is bad on a distributor? The haynes manual says turn the rotor clockwise, and the springs will pull it back to the original position. Mine doesn't do that. When using a timing light, the timing advances with the vacuum hoses attached, and revving the engine(Timing set at 5BTDC) When i take off and clamp of the hoses, the distributor shows no advancing while revving the engine.

Time to take it apart and clean/rebuild it? 1987 SR5

[dr.occa]

If I'm following your steps correctly - you are correct: the timing should still advance with the vacuum hoses disconnected because the centrifugal weights in the dizzy will advance the timing. If you've got your timing light on the timing marks and the timing doesn't change as you blip the throttle then your mech. timing may be galled up. Pull the dizzy and shoot some WD40 on the springs, the weights and the moving "stage". Then just work it in by twisting the mech advance by hand.

[BlackStar]

The dizzy is 25 years old, it probably could use a good cleaning. I'll also check the air gap before i get to into the deconstruction of it, according the the manual, if its outside the tolerance, just get a new dizzy. Hopefully the springs are still good, i dunno where to get new ones.

[dr.occa]

Rockauto.com is you're best bet for NEW ones but they're not cheap. You might consider one from a tercel 3AC. You would just need an external coil and to reroute a couple of wires. You can then more easily run an after market coil of your choosing e.g. Pertronix, MSD, Accel, etc...