I like the glass/slate call for getting their attention and the diaphragm for getting them to stick their head up.

Sometimes I use the diaphragm to get them really excited if they' re being a little tough. Try cutting off their gobbles (before they finish gobbling) -it usually makes them double and triple gobble---keep doing it ' til you think your head is gonna blow up. When they go quiet --doesn' t work every time (nothing does) but when it does --GET READY!![>:]