Yes. Be warned - a dirty cutting device is not a good thing. Flame sterilization.

Also, what are simple ways (like I can't build an ozone generator right now) to reduce contamination in the casing material?

Get a fine mist spray bottle, fill it with commercial-grade 3% hydrogen peroxide, and mist all of the casing material with it before layering it over the mycellium. After that, just mist the casing every once in a while (like once a day) with it. Everything should be fine.

Oh, and do not store h2o2 in a container made from non-opaque material. Light breaks it down, that's why it's shipped in those dark-brown bottles.

Did you use the pf-tek for your jars? If so, then have you removed the tape from the holes? If you haven't, I suggest it. The vermiculite seal will ward off contamination, and your cakes already being so far into the colonization process should finish nicely. If that's what you've been doing, then just KNIFE the little bastards!