So I seen the mod done in another post. So I tried it and it worked great I was getting around 4.5A across the emmiter. But then when I put everything all back together. I could only get modes 1 &2 and the strobe was at level 2 output. So I’m stumped. Can anybody help me with this issue. Is it likely that I have fried my driver.
Hmm…I haven’t had any problems with mine at around 4A. Not sure if it relates to the problem you’re having, but maybe check to make sure the stacked resistors are not contacting the battery plate?
Pictures of the mod?
You may have a short that’s bypassing the driver. I’ve seen this with HD2010s where the reflector is touching the minus side of the emitter. All modes look like high and a tiny little bit of pulsing is noticed in strobe/SOS. Looking at the pics here it should have been an easy resistor mod.
Wow, I like the UI on this light. Why did I not clue in that the TN31 has a ring for control? And Jake has a real good price on this, shipped to Canada. Must resist…
Could it be just a simple misalignment of magnetic control ring (and/or driver)? At lest that would be my first guess.
=> disassemble, align & assemble again.
The same thing happened to me. 
After doing the resistor mod, I assembled my K40 back only to find out that only two modes are functioning which freaked me out. Upon closer inspection however, I noticed that the driver was not installed back properly. 
In the K40’s driver PCB, there is a portion wherein the edge/ground is wider. This is shaped exactly like the bare/exposed portion in the pill. This should be placed directly over that bare portion and NOT the little ‘switches’ for the different modes. This should solve your problem.
So I figured out what the problem was. It seems there is a problem with the switch. Has any body else had a problem with the switch. But I can’t understand why the first two modes work. I didn’t explain the problem fully. The led lights up correctly on the first two modes, Then it stays on the same brightness level to 6 and strobe. I know is the switch coz I got another of these lights nd swapped the body.
You missaligned the magnetic sensors as always mentioned...
No it seems to be the tail switch. I swapped the tail switch from the modded light to the new standard 1 nd it did the same thing on the standard light. I’m just confused how a clicky stich does. Clicking it does not turn on or off.