First,what part of the country are you located in??
Second,good news is that parts are STILL around for your New Service 1917. Practically every day oneBay some are listed. But a caveat,as with "used parts" for anything,what you buy may NOT be better than what you have,unless what ya have is totally broken/missing.
Colt FACTORY will NOT work on these guns as they are TOO OLD. I thought that Colt still would work on original Single Action Armies,1873-1940,but was told this is NOT the case anymore(despite the fact that the 2nd Gen. of SAAa are mechanically the same(1956-78).
Colts are NOT to be worked on by the average gunsmith! If that sounds harsh,or elitist,so be it(and I hope dfariswheel will give me "backup" on this statement.) I have taken a lot of "flak" on stating this around some S&W loving friends, Simply put,would you take a Ferrari to "Fred's Fix it Shop"?
Colts are tricky,and as they have become scarcer in recent years,with very limited productionof the older leaf spring actions like your 1917,some newer smiths haven't even been trained on them.
They require a lot of hand fitting,and this is time consuming,and one reason Colt introduced the MarkIII models in 1969.
Hopefully,your 1917 will be something simple,but older Colt D.A.s,while looking "simple",with fewer parts,compared to Smith and Wessons,have parts doing more than one function,and timing is the key.
Anyway,my now deceased gunsmith,who kept working until his late 70's,and my Master Sgt.Armorer in the USAF 40 years ago said this about Colts also-and taught me "enough" to repair most of my older Colts.
Try and describe what the exact symptoms are,here on the Forum,and probably dafariswheel can give you some idea as to the trouble.
Speaking of 1917 Colts,which is a New Service model,just came in from my backyard range after putting 50 rds. through a 1916 made .44 Special. Got a bore cleaning job,as the "great load" a friend told me to try with swaged 240gr lead hollow points,really leaded up the barrel!
Good Luck,welcome again,and keep us posted!
Bud(New Service "lover") /forums/images/graemlins/grin.gif /forums/images/graemlins/crazy.gif