ttl heads?

X-acto knives work well. Just carve through -- heating the head helps. The part under the chin I usually take my hot glue gun, heat it up, and apply pressure downward, which will melt the plastic, then carve what you took off with said X-acto knife. It'll take a while -- Usually for me to get the head just right, it'll take upwards of a half hour. But it's all worth it.