4 wheel drive lever

Hi i have a 1975 series 3 and the gearbox is fine but the 4 wheel drive lever doesnt, it is all connected up and moves the shaft in the gearbox but it never engages 4 wheel drive and it doesnt have any pressure on it which gives me the thought that it needs adjusting. I have only had the car a couple of months and it has never worked.
if anyone has any ideas it would be very useful if you told me. oh and yes when i engage the low box the 4 wheel drive system works.
thanks

ieuan

does it lock down, i no when i had the spring of mine while doin somthing it kept dropin in to 4x4 on its own so it doesnt realy take any pressure.

I had a similar issue, the spring had broke and would not stay in 2wd, check the book for the detent spring, you can get it out with the box still in the vehicle.

are the exposed shafts free of rust on the front output housing if not used these can rust up and prevent the shafts moving to engage 4 wheel drive whrn yellowknob pressed,
have you checked your gearbox/transfer box oil levels

hi
no it goes down but it wont stay down. i have just put the spring on it and so before it was down all the time but i still had to engage low box to get 4x4.
thanks

ieuan