Forcing the use of one index instead other.

Hello there!

I have two index with a same field into them like this:

create index numberfail on Events (numberfail);
and
create index failtype on Events (numberfail,eventtype);

then i ran explain analyze and always took the numberfail index but i wish the failtype index;

this is the query:

SELECT * FROM events WHERE numberfail=194 AND eventtype='XXX';

What should i to do to force the use of failtypeindex????

I though maybe if i delete the index numberfail could works, but i don't know if the another program
will fail if the numberfail index does'nt exists.

well, thats all for the moment and i appreciate your time in reading this mail!!!
See you.
--
SENSA Control Digital.
Ing. Edmundo Robles Lopez.
Analista Programador.