Do you have the greenbook for D24? I have for the D24T so if you do we can compare nozzle types and POP between the two. I believe the injector bodies are the same, also shared with the VW engines (and Mercedes, and possibly GM) of similar era.
I (and others) have had excellent results from Monark brand nozzles, the model which is a slight upgrade from stock nozzle specs, similar to the VW GTD type nozzle. The particulars are still here in D24T forums.
Since I have not been in the market for injectors or nozzles for years I have no advice as far as pricing or availability.
The differences between D24 and D24T injectors are mainly the higher POP setting for the T (simply more or thicker shims) version and possibly the nozzle spec. Bodies are the same.
Leaky spill nipples are usually caused by using a socket lacking sufficient clearance for them (they get dislodged and pinched inwards), or other sloppy handling. Being a press fit, they can usually be carefully reseated with a small hammer and soft punch to seal better.
Do you have access to a POP tester? Small ultrasonic cleaner? Ultra-clean work area?
VinceWaldon.com was my goto when I rebuilt mine.
HOW-TO: Rebuild Diesel IDI Injectors - VinceWaldon.com