I've been working on this...
The problem is that Orient use 1.6mm diameter spring bars (and 1.6 seems to be custom made or something as I can't find them online) which I bent going down a waterslide
The only other standard diameter that would fit the strap are 1.5mm
I ordered the next standard size up, four 1.8mm spring bars (£1 from the bay) and they barely just don't fit in the strap by .05mm without the hole on the strap being bored/reamed out.
So I took it to a jewelers who sent it to a watch repair place and it seems they just put on 1.5mm spring bars and charged me £12.50 for the privilege
I might be wrong but it seems like an engineer firm would need to carefully bore out the strap unless there are ideally 1.75mm spring bars out there