Hi, Yes the splines, on the repro are loose. It's the spider splines, not hub. Yes they will wear. This just sucks! Be sure to loctite the clutch nut is all I can say.
Of course you could loctite the splines. That would work. Heaven help you if you needed to take it apart again. I guess you could heat it to 300f with heat gun. Rubbers would be junk anyway. I might do that next time.
I was going to machine spider square again, resurface back plate. Turn the shoulder deeper on outside to compensate. That would work. But.... The back plate is hardened. My lathe wouldn't touch it. Must be surface ground. I don't have surface grinder. I'd already filed grooves & they needed it again.
So I had to buy new one. Could not find genuine Triumph NOS. All the NOS parts were NOS Harris, NOT!!! Triumph. This is huge problem on eBay with NOS. Yes it's NOS, but actually is Harris or Wassell. Same crap as they still sell new, but with light layer of dust & rust. Luckily I'm 70 now so only need to get by another 5-10 years. Maybe less? Who knows? I don't even buy green bananas.