I have 10+ years on that shimano dynamo you describe. I insert the solid wire (not stranded) through the block and snap on the block. I also used heat shrink tubing to anchor stuff together. It never failed on me once and I ride rain or shine and all winter long in Chicago.

I just finished the same process on that same SP dynamo (new commuter build) and maybe over did the sturdiness (heatshrink + doubled-over wire so the block snaps quite snugly (bigly)). Many thanks to Drew for that bannana plug idea. I will add them so wheel removal is easier.

[adding: I also use heavier tires (schwalbe marathons) so I don't get flats. The old commuter never had a front flat in 10+ years. I only disconnected the dynamo once to do some brake maintenance and preemptively replace a worn out tire]