Walkera 5-5 Co-ax - can't get full throttle

[AMH82]

Hi guys, new here, and yes, I own a Walkera 5-5, but I hear they are better than they used to be so don't go too hard on me!

Since I've had my 5-5 (2nd hand) it's been suffering with poor lift, even with a freshly charged battery it needs full throttle to get a slow lift, which then quickly turns to a slow fall again.

I have noticed that I am not getting the red LED on, on the 3in1 when I am at full throttle on the transmitter. I am told that the red LED means full power so this would explain my lack of lift.

The only way I can get the red LED on is to set the throttle trim to 30%, 40% to get a strong red LED. With the trim like this I can get good lift, but have been told the trim should be zero otherwise the 3in1 speed controller does not operate correctly.

What could be the problem?

I have two batteries but not sure how old they are, the charger is the original Walkera one that many said wasn't very good and I'mhopefully going to replace it with a proper Li-Po charger. Is it possible that the batteries are poor? I'm guessing maybe not as I can actually get full power, it just needs some trim.

The lower rotor starts up a fair bit earlier than the top, should this be better synced? Using one of the pots on the 3in1?

Any ideas of what could be causing the problems? Weak transmitter batteries maybe? The Walkera sign is fully lit though.

I have ordered a new Li-Po to try but I'm not convinced that will be it.

[AMH82]

Had a bit of a play and think I've worked it out.

I was re-levelling my swash, as doing it by eye I was still a bit out, and so had re-centred all trims, throttle trim to zero.

I wacked the throttle up to max and the red LED on 3in1 came on, strange I thought, but had been wondering if maybe it was to do with the lag/lead between upper & lower rotors. Sure enough as I adjusted the rudder trim the 3in1 red LED got brighter to one extreme and then went away to the other extreme (can't remember which was which).

So, once I have got my swash levelled rather than adjusting rudder trim on the transmitterI will adjust it on the 3in1 which will then hopefully give me full throttle under normal trimming.