The cracked pulleys are almost certainly original. 9-tooth plastic pulleys were used on late-model Record and the first year or so of the Nuovo, before switching to 10-tooth. 9t pulleys in usable shape are rare, and expensive when you can find them, unless you get really lucky.

Jim Merz has made new (repro) 9t pulleys and has offered to make more if someone sends him the metal "hub" parts so that all he has to make is the plastic bit. They are almost indistinguishable from originals, but rather expensive ($100/pair I believe), so only worth it for an excruciatingly-correct restoration project. Most people will forgive you for putting on newer 10t pulleys, and if anyone gives you grief, stop talking to that person!

Note, I am not complaining about Jim Merz's prices. $100 is not a lot to have something custom-machined by a master like Jim; he's not making much money on the deal actually. It's a hobby for him. All I'm saying is you gotta really want it, to pay such a price for such a tiny detail.

No offense to OP's mech intended, but it's probably not in good enough shape (chrome etc.) to be worth putting Merz pulleys on it.

Speaking of Jim Merz, another wonderful service he offers is unriveting and re-riveting Campy derailer parallelograms. He machines his own bushings and pins with tighter tolerances than the originals, and he's made the punches to make the rivet ends look like original. So if one were crazy enough, you could disassemble all the parts and re-chrome them. You can usually find one with nice chrome for less money than all that would cost though.

But ability to put the parallelogram together from parts opens some interesting possibilities. I've had him graft the top knuckle from a Campy Sport (not Gran Sport), which has a sprung pivot, onto the rest of a Record parallelogram. Making what Campy never made back then (that I know of) but they could have: a mech with sprung pivots top and bottom, like a Simplex Prestige. This is pretty cool for Campaholics who have gotten fat and need low gears. I have it on a bike with a wide-range triple and a 31t large freewheel cog, capacity not maxed out. Without the sprung top pivot, that mech is mostly limited to small differences between the chainrings, like the half-step setups racers liked back then. With a wider span between the chainrings, you can normally only use small corncob freewheels. I also had Jim graft the Sport top to an older Gran Sport (bronze/steel, not the later alloy one), so I have a good derailer choice for lower gears on an older bike where a Record would be too new. And technically period-correct since anyone could have done this BITD, and maybe someone did.

Actually the hybrid mechs are a bit of a PITA; aside from the expense of buying two vintage derailers and paying Merz to graft them, it is also much trickier to install on the bike. I can go into more detail for anyone who's interested but I'll stop now since I'm "derailing" the discussion. Pics of my Record hybrid here. Here are some pics of the Gran Sport hybrid.

Mark B