[Graham Freeman]

I had a similar problem with my cabriolet.
I replaced the rods with stainless steel and threaded the ends.
The nuts originally brass, can be turned from solid stock brass to get the 45 degree shoulder and drilled down the centre while still in the lathe and threaded.
The head has a slot.
I butchered a small screw driver by taking a central piece out of the blade to enable tightening of the screws.
Hope this helps.
Graham