Hi Alf,
I think we are talking apples and oranges. ERA uses a more modern round motor with a 5pin connector that I believe also integrates the park switch. Similar to this:
Wiper Motor - Under Dash with Rack 12 Volt for vintage & classic cars
You are using an older square body motor which is totally different, uses a different rotary switch and has a different style of park switch. Do you have a spare rotary switch to try with your wiper motor? That may help you determine if you a rotary switch issue, park switch issue or a wiper motor issue.