My eagletac p20a2 mark II has a bit of flicker. I cleaned both contacts on body, switch ring contact and contacts on head with rubbing alcohol. I also tightened switch ring. I'm not sure what elso to do.
Try taking off the ring that changes modes, then clean that up, just make sure you know how to put it back on. If that don't work, contact EagleTac or the dealer you purchased it from. If it is an authorized dealer, you have a lifetime warranty. Being the MKII, they could just send you a new module.
Cleaned all the thread and contacts on module and body, still flickered. I decided to take the switch out and clean the contacts there, bingo no more flicker.