Help with windshield wiper switch

[rdlackey]

This is in my 1957 truck. It appears that the windshield wiper motor has been replaced at some point in time.

This switch, although connected, does nothing...just turns right continuously and left...the same. It does not "click" into a postion. The wipers do not run.

I am thinking that I need a new switch, but am having trouble identifying, since there is NO part identification on this switch.

The back side has four terminals, marked "B", "P", "H" and "L".

The four wires connected to these terminals respectively are RED, GREEN, WHITE and YELLOW.

Any help would be appreciated.