does anyone know what the part is that is on the end of the shaft nearest the motor. my grub screw came loose last night when i was shooting a new video and the whole shaft slid out enough so that the prop would not spin. i had to go get it in the middle of the lake and it was dang cold! is there a better replacement for this part? (if you know the one im talking about) b.t.w. there is a new video uploading to you tube a little more action in this one...thanks in advance for any help.