The old pumps (like yours) can be overhauled but it is not cost efficent. So a visit to the local parts house is in store.
My grandpa swore by the black pepper (temperary repair). But as a more permanent repair replace the pump.
What ever you do never NEVER!!!!!! use liquid glass or stop leak on your vehicle unless all other means or repair are exhausted.

I didn't do it, no one saw me do it, you can't prove anything! "Bart Simpson"