Pruning my rambler

How do I get my rose back to the tall flowering mass that it was a year ago?
I know the usual rules (as per this post) but if I do that, I'll end up with a very short rose that won't go over the arch or up the garage wall.
When it says shorten side shoots - isn't everything on a mature rose a side shoot? What happens if I don't cut that oldest stem to the ground? I'd love to know the "why"s behind the instructions
2023:

2024:

Now:

 

I think the idea of hard pruning is to create new, vigorous shoots rather than rely on a mass of old twiggy branches to produce flower buds.

I have an Adelaide d’Orleans which was planted against a pergola on a steep sloping garden. the height of the pergola where the rose is planted must be well over twenty feet, whereas the opposite “wall” of the pergola is just a normal height. Strong wooden cross bars join the two sides at “roof” level. The total length of the structure is about thirty feet.

Over the years, the rose has grown and been pruned but as we have got older and less steady on a ladder the older branches have been impossible to reach. we now have a veritable crow’s nest over the top of the pergola. Dead twigs mix with live but elderly branches. The rose is happy and flowers well, but it’s not a thing of beauty so much as a wildlife haven. Birds nest in the twiggy topknot.

 

My personal approach is to leave a Rambler to ramble.I just let them do their thing unless they become unruly and just prune off anything that may get in the way