electric stik

[hybrid]

I have had an great planes electric Stik for about three years and it has flown great up until now. It has never been crashed, however I have some strange stuff going on. When the plane goes into the wind it wants to climb, and on going downwind wants to dive. The CG is spot on and I have checked everything on the plane. I even tried some washers on the motor to create down thrust which made little difference. I have added weight to the nose which now makes it nose heavy but it still wants to climb.
Any idea on what I have missed.
Hybrid

[Glacier Girl]

Hmm, maybe take a look at the wing saddle area. It could be the wing AOA has changed. Since it bolts on at the back, wood may have compressed and it's dropping the TE of the wing. Which would make it climb in a head wind , and loose altitude on down wind.

But if it's just climbing in one direction and "diving" in the opposite you got me on that one.

[flydiver]

Making it nose heavy may make it worse. Heavy nose at low(er) speed wants to drag the nose down >> elevator trim needs to be put in to compensate for level flight.
Now...up the speed, excess elevator trim creates ballooning up.

You might want to check out these articles on trimming, esp. the 'dive test'. Even though the strong emphasis is on not being tail heavy many folks set up their planes way too nose heavy.
Chapter 6: Intermediate Trimming
Trimming Your Bird!

Definitely check the wing root and incidence as suggested by GG. If that is messed up you need to fix it first. Also check the horizontal stab to make sure it isn't bent/loose. You don't have to crash it to knock that loose in landing over that long a period.