I took my wiper system apart, cleaning connections, pulling out the rack and cleaning it and lubricating with some clear synthetic grease I had etc. under the assumption that any 26 year old grease would be getting pretty stiff. Mark the different sections with marker or better yet scribe marks so you can get them all lined up again easily. Also mark the parking switch mounting screw so you can get it back in the same position or close to it with minimal adjustment. It worked before but it's been fine since. I didn't take the motor apart to clean any commutator or like parts because it seemed pretty sealed and was working so can't advise in that area.
Check the wiper boxes for wear after cleaning them and lubricate them.
Word of caution. Protect the copper parking switch actuator with a stiff baggie as it is vulnerable and can be damaged while you're cleaning the long rack. As mentioned you may have to adjust the parking switch when you get it all back together to stop it from continually wiping but that is quite easily done relatively in situ.
As Mildred said, cleaning and lubing should be done first before any money is spent on parts.
I bought a grease gun tube of clear synthetic grease with the belief that synthetic grease tends to be less washed away with water and it is lighter than regular type grease and seems to work well.
- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT