4 station Tool post never stop when changing the tool number

CNC Control system of the CNC lathe machine:

GSK980TD/DA98A, double speed spindle motor, 4 station tool post

(Other CNC controller like GSK980TDa,GSK980TDb, and AC servo driver DA98B, DA98D, same solution)

How to solve the problem:

Problem detail: Press the tool change key under the JOG mode, the 4 station tool post runs and never stop. Input T0100 or T0300, under MDI mode, the same thing happened, but input T0200 or T0400, the 4 station tool post can change to No.2 or No.4 tool. So we can see the problem only on No.1 and No.3 tool position, No.2 and No.4 are fine. It could be wiring of No.1 and 3 has problem. So we can take out the tool post cover (This one is not using Hall conponent), the 24V connects to CNC controller directly, the tool signal transmission uses short connecting of two small sheet coppers, and they are rusted. Get rid of the rust and then the 4 station tool post resume to work.