Lumintop Terminator TD-15 problems

The light doesnt seem to be making good contact as it will flicker and be really dim or stop shining. I put fresh batteries in but still wont work right. Any ideas where I can look?

clean all current conducting surfaces with alcohol and cloth or q-tips

look if springs are deformed/too short
tighten all retining wings

see if shorting the tail with wire instead ztail cap fix it, so you can eliminate this part

if you can run driver on a external power supply or battery with leads holding on the spring and driver ground ring

This is the basics you should do before needing any instruments to measure stuff further out