'79 wiper motor a bit weak

Motor works but the wiper arm movement is a bit weak - is this normal or is motor about to die?

 

It will if you don't clean and lube your linkage, especially the wiper spindles. They're the things that normally seize up.

 

Ive been through the motors . On these buses and other vehicles.
There are the answers on this forum with a simple search
Anyway ...
If you want to get a few more years .
Pull back the dash . Acces to the right side of bus,
And remove the wiper with the linkage .
In one.
Put new rubber seals on the spindles.
The motor if full of 40 year old hardened grease ,
Take it apart . Clean and lightly re grease . Youll see it .
Sand the brushes .on the motor.
Mark the spindle orientation on the arm .
If your brave ,,
It wont be lightning fast but it will get you throuhgh a few more years.
If they were cheap .i wouldnt be writing this,.,,,,
Enjoy

 

dodgy earth to the motor can do this too