Welcome to the Pet Rescue Community
Do you need help with your game? Ask the Community for help.
The line blasters that just drop within the game board are entirely random. It can make some levels extremely frustrating when you rely on the line blaster to pass, but none appear.
My advice in levels that you're having trouble getting enough blasters is to also look at the number of moves you have left. Sometimes it is better to quit the game and start that level again if you play a certain number of moves and still no blasters drop.