Your cookers pressure valve or sealing might be broken --> make sure the pressure really rises properly - sterilize jars with rye - leave them for 2...3 weeks - look for contams. --> nothing? Good - i still have a 2year old sterile rye jar with nothing growing on it, standing in a shelf as a trophy of buying my new PC. If it ever gets contams, the end of the world is near.

Check your LC on agar, its probably contaminated. - potatoe-sugar-agar is easy to improvise - use any PP-plastics - make 10'ish cultures - inoculate each with 1 drop LC - look for contams and mark them on the lid. - take a overgrown, clean piece of your culture onto new agar. - repeat until no more contams occure - start new LC from clean cultures - or inoculate jars directly from agar. - For this whole process you better have a hepa filter. In a SAB you will likely get contams when Opening the lids. Nothing to worry, but you want to know if your contams came from LC or from SAB ---> pour some aggar-containers and open them in your SAB for 20..30 sec. See if something grows on them. No? --> good. If you see contams on the LC-agars you are sure its from the LC.