Chevrolet Repair: wipers, buick lesabre, screw driver

Question
I have a 1984 Buick Lesabre 5.0 V-8 when I turn my wipers on
sometimes they wont come on for several minuted then
make 1 or 2 passes then quit other times they work normal I   
have replaced the all in 1 switch cruze,turn
signal arm with wires I'm not sure what could be
wrong

Answer
GOOD MORNING BILL,DO YOU HAVE A TEST LIGHT OR VOLT METER ?? IF NOT YOU WILL NEED ONE..WHEN THIS HAPPENS OPEN THE HOOD AND PROBE THE WIRING HARNESS GOING TO THE WIPER MOTOR AND CK FOR POWER WITH THE TEST LIGHT OR 12 VOLTS WITH YOUR METER..IF YOU DO NOT HAVE ONE OF THE ABOVE,TRY TO POOR MANS WAY OF CHECKING,TAP THE WIPER MOTOR ITSELF WITH A SCREW DRIVER HANDLE OR SMALL HAMMER,[TAP-TAP NOT DESTROY IT] IF IT STARTS WORKING YOU KNOW THE MOTOR IS THE PROBLEM..IF NO CHANGE THEN YOU WILL FOR SURE NEED A TEST LIGHT OR VOLT METER. TO CK TO SEE WHICH WIRE IS HOT WHEN THE SWITCH IS ON GET IT SO THE WIPERS ARE ON AND THEN PROBE IT SO YOU WILL KNOW WHICH WIRES SHOULD BE LIVE WHEN THE WIPERS DO NOT WORK.. I SUSPECT THE MOTOR IS FAULTY.THE LAST THING YOU COULD TRY IS WHEN THEY DO NOT TURN ON, GRAB HOLD OF ONE OF THE WIPERS AND GENTLY PULL UP ON IT TO SEE IF THEY WILL TURN ON LIKE THIS, IF SO, WIPER MOTOR IS BAD..FLAT SPOT ON THE MOTOR ARMETURE WILL CAUSE THIS. LET ME KNOW HOW THIS GOES FOR YOU, AND IF YOU NEED MORE INFO GET BACK TO ME..TOM...