Help! resurrect a 1986 Conquest Chrono

Hello,
I need your help.

I was approached by my uncle to revive his Longines Conquest Chrono which dates from 1986.

the pushers were tinkered with because the original ones had broken and had become impossible to find.
moreover, the mechanism seems very tired because it stops very quickly.

Longines no longer manufacture the parts.
what are solutions are possible apart from buying an equivalent model and cannibalizing it?
if you have any ideas to find parts i am interested.
I did not find much on ebay

Do you have any photos of the movement?
I am guessing that it has the Valjoux 7750. If this is the case you can easily find parts for this movement.

I currently have no pictures of the mechanism.
you are right, normally this model has a caliber L674 which would indeed correspond to the Valjoux7750.
I will ask my watchmaker which parts need to be changed.

and for the pushers, would you know where to find them?

I suppose if you are patient enough to wait if something comes up on eBay….

I feel this quest is going to be epic...