Lubricate the linkage and pivot points under the wiper arms. I use WURTH HHS-K because it doesn't collect dirt and crud like some other options. It's great for door and trunk hinges and all of the latches on our trucks.
This is the product info page at WURTH USA
https://www.wurthusa.com/Chemical-Product/Lubricants/Specialty-Lubricants/HHS-K-Hinge-Lubricant/p/0893106050I've been looking for a couple of known dead late 80's GM truck wiper delay modules to try my hand at repairing them.
Old electrolytic and older oil filled capacitors eventually stop working. I've been able to repair several dead 78-83 delay units for some local guys using fresh electrolytic capacitors.
I'd email you a PDF of a USPS shipping label if you're interested in being a Guinea pig by plugging in a repaired module to test whether it's fixed. You print it and tape it to the box and take it to the post office. If you're interested PM me your email.