Steve asked:

It seems to me we are told it is a sin to set a slave free and a Mitzvah to free a slave. Please explain this to me so I can better understand.

The Kollel replies :

In general, it is a sin to set one's Eved free. However, if there is a Mitzvah involved, such as the case the Gemara mentions where he was needed for a Minyan, then it is allowed.

D. Zupnik