How can i adjust it without the electric switch

 

You have to run a plus wire from the battery to the orange wire on the motor receptacle. I think it is orange. It would be best if you got yourself a service manual which would give you the wiring diagram that shows the wire colors. An alternate way would be to disengage the transmission shaft and move it manually.

 

It depends on which seat you have. My 86 uses a single motor with three clutches for fwd/back, front up/down, and rear up/down. The motor leads are reversed in the switch (power and ground) to run the motor fwd or backward. The clutches are either engaged or disengaged. To move the seat you must simultaneously power the motor and engage the correct clutch.

There is also a version of the power seat that uses three independent reversible motors. In that case, you simply need to power the correct motor.

Starting in 1986, GM cheaped out and removed the relays, instead running the high motor current directly through the switch. This causes the switch contacts to burn out. It is possible to disassemble the switch and file the contacts, but it is not for the faint of heart. The inside of the switch uses a series of rockers and contacts that require watchmaker skill to adjust properly. I am not aware of any repro switches being sold.