When I saw, "3 bills to rebuild the cartidge" I thought, "get a new $300 TT that will sound better anyway".
What's the deal with the arm/cartridge combo? Can't other brand cartridges fit on the arm? This is really weird, but I do not know B&O TT's.
Now, if you like what you have, keep it.
But....I'd like to see you audition, in home, a $300-$500(Rega or Project) TT set-up and then decide.
And...should you quit vinyl, I'll take your old blues LP's.
I just took a quick look at the B&O arm/cartidges, and it does not look like you could pop a nice sounding, budget Grado on there.