I have not had this problem (knock on wood), the 4 females that laid for me I:

1. removed momma from eggs & placed her in a tub of tepid water with a couple drops of
dish detergent to soak.
2. set up eggs & put them in bator.
3. clean tub, wipe out rack slot with bleach & water solution & let air out for about 30 minutes.
4. put momma in clean tub & put back in rack.
4. offer 50-60g rat.

Every girl took their rat immediately.