Power reverse indicator - Lecoultre

[Jr86]

Hi all, 

I serviced my Lecoultre Powermatic from 1948. However when putting back the power reserve indicator wheel, the wheel does not match with the power on the watch.. first, I tried putting the wheel when the watch was fully wounded, setting the wheel at 40, then when the watch was unpowered, setting the wheel at 0, but in the end when the power  drains, the wheel gets between 5 and 10. Any ideas ?? Advises?

[AshF]

Incorrect mainspring?