Remington Model 24
One VERY IMPORTANT consideration in using the Model 24 is that it was designed and manufactured for with .22LR STANDARD VELOCITY ammo only. Use of High Velocity ammo will cause some serious damage and/or preliminary wear on the innards due to the higher energy output to both the bullet and the rifle block, extractor, etc.
I have been able to find some miscellaneous parts by doing a google for Remington 24. Some were on EBay, some not.
Good luck using it. It was my dad's, now mine, and my grandsons will enjoy using it soon.