A broken trigger/bolt spring is a very unusual failure, despite the rants about 'soft' Italian gun parts. Your description gives very little information to use in diagnosing the root cause and thus taking corrective action.
I assume by 'broken' you mean 'fractured', as in broken into pieces. Where did the fracture occur, and what action caused the spring to break? Did both springs break at the same location, and did the same action result in the break both times? When you disassemble the gun did you notice any other anomalies? Were there any unusual problems in reassembling the gun? Did you attempt to dry fire the gun after assembly, and was that successful with no incidents? When you draw back the hammer, how many clicks do you hear, and when do they occur?
Without more information the only action you can take is to replace the spring. I recommend the Heinie Colt SAA wire trigger/bolt spring available from Brownell's: http://www.brownells.com/aspx/NS/store/ProductDetail.aspx?p=6875&title=SINGLE%20ACTION%20TRIGGER/BOLT%20SPRING
although you can certainly fabricate one yourself as emishi did.
I assume by 'broken' you mean 'fractured', as in broken into pieces. Where did the fracture occur, and what action caused the spring to break? Did both springs break at the same location, and did the same action result in the break both times? When you disassemble the gun did you notice any other anomalies? Were there any unusual problems in reassembling the gun? Did you attempt to dry fire the gun after assembly, and was that successful with no incidents? When you draw back the hammer, how many clicks do you hear, and when do they occur?
Without more information the only action you can take is to replace the spring. I recommend the Heinie Colt SAA wire trigger/bolt spring available from Brownell's: http://www.brownells.com/aspx/NS/store/ProductDetail.aspx?p=6875&title=SINGLE%20ACTION%20TRIGGER/BOLT%20SPRING
although you can certainly fabricate one yourself as emishi did.