Changing roof hydraulic hinge rams

[enuff_zed]

Possibly a question for the US members as the issue seems more common over there.
I’ve already asked Number5 btw and whilst he’s given a lot of good input I feel I need more.
Got a car with a ram that has failed internally. Roof goes back a few inches then gives up and collapses back to the windscreen again. Can also be moved by hand without the need to depress the bypass plunger.
No external leaks and no loss of fluid according to the constant reservoir level.
As both rams feed from a common union it suggests that once one ram fails then the fluid takes the path of least resistance and both hinges fall at the same rate.
So the only way to be sure it’s fixed is to change both together.
I have a matched pair ready to fit and here is where I need help.
How do I ensure both rams are set at exactly the same point of travel so the roof goes up and down straight and doesn’t end up standing angle?
Is there a way to rig the rams or is it trial and error?

I’m hoping someone has done this and can offer some advice.

 

[enuff_zed]

Well it seems no one could help me with this, but I’ve done the job now so I’ll update it for future reference.

If you remove the roof from the car and fold it into the lowered position you will see that the hinge arm stops against the tails of the mounting bolts that secure the hinge arm to the roof frame. Therefore it is a simple matter of ensuring that the replacement hinges butt up to these bolts when fitted. Do both sides the same and the roof raises straight and true.