ISRO expressed concerns on restarting the Liquid Apogee Motor (LAM) for Mars Orbit Insertion (MOI) after a long coasting period of its Mars Orbiter Mission (MOM). ISRO has redesigned the LAM plumbing to isolate the fuel / oxidizer lines used for Trans-Mars Injection (TMI) and instead use separate (and fresh) fuel / oxidizer lines for the MOI manoeuvre.
ISRO will test fire the LAM ahead of MOI for a short duration to check its health. Plan B, if it does not pass the test, is to use the attitude thrusters for MOI to enter a mission salvaging orbit around Mars.
Both the LAM and the attitude thrusters use the same fuel/oxidizer from shared tanks:
How is it then, that the thrusters are considered more reliable than the LAM?