Water is only coming out of the first few drippers

If you find that water is only making it out of the first few drippers, it is likely you have the cleanable dripper installed the wrong way round. 

The new style dripper has a long stem and a short stem. It is the grooved long stem that needs to be pushed inside your irrigation tube. The short bulbous end is where the drips will emerge. 

If you have stretched the tube, it may be worthwhile snipping a short length off the end of the tube before you put in the dripper the correct way, to ensure it is seated correctly.