Take a clear photo of the back of the clock, just the works, not the legs.
Someone with the Horolovar repair guide might be able to identify it.
If it has a disc pendulum there might be a number stamped or written in pencil, this should match the main number, if the pendulum is original. 3 or 4 ball pendulum will not be numbered.
I read somewhere (maybe the tube) that you can cure a lot of evils if you wind the spring up as you would into a mainspring winder (though a MS winder would be too large and this would have to be done on the flat of your bench for example) until it is fully and tightly coiled. I gather this gives it its shape back and you can move on from there. Maybe a bit of an ask for your spring though !! Maybe worth a try as not much to lose !!