Mitchell SAA by Uberti: Hammer Safety Parts?

[JeffKnox]

Hey Folks;
I have a Mitchell Single Action Army .22 that was purchased back in around 1983 and was, I believe, manufactured by Uberti.
It has a toggle-style hammer block safety that is actuated by the trigger landing in the safety notch of the hammer, and governed by a plunger and spring in the top of the hammer, retained by a small set screw.
I have lost that plunger, spring, and set screw.  
I originally gave this gun to my grandfather.  After his death, the family returned it to me and I subsequently gave it to my grandson.  It apparently rattled out while he was shooting one day and was lost. 
Can anyone tell me what these parts are officially called and ideally what the specific part numbers would be?  I don't find a clear listing on the Uberti website, and I'm not sure that the parts I've found on other sites are correct for this gun.
I'd really like to get this gun repaired and functioning for my grandson.  Simple repair, if I could find the correct parts.

If I have to, I'll steal the parts from my matching Mitchell .45 Colt, but I'd much rather have them both up and running.
I'm planning to be in Houston for the NRA Annual Meetings and Exhibits in April, and will talk with the Uberti folks there, but knowing correct nomenclature and maybe part numbers in advance might help.
Any guidance would be greatly appreciated.

Thanks,

    Jeff

[Boggus Deal #64218]

VTI Gun Parts, Taylor’s & Co, Cimarron Firearms. All carry Uberti parts and have good diagrams.

[Colorado Coffinmaker]

 

You will be hard pressed to find ANY parts for the gun.  When Uberti discontinues parts and or whole guns, they no longer support "parts" that are now obsolete.  Good Luck.

[Larsen E. Pettifogger, SASS #32933]

The safety in the old Mitchell's was a safety Uberti put in to meet import restrictions.  Was never very effective and the guns function without them.