Ignition switch problem

[68haywagon]

My 68 truck's ignition swicth does not return to the "on" position after it starts. You have to turn it back manually to the "on" position. Also the acc, off, on, and start positions have no identifible feel to them . I usually turn the truck off after it starts because I pass the "on" position . Is this a bad switch or just the lock tumbler? Any one else have this problem?

Thanks in advance

Mike