We were quite lucky then,we had keys to the machines and pool table,we emptied them,banked the money,after changing it into note form,this was handy as it gave us change,the company would than come and check we had no problems and upgrade the machines if we desired and we just paid them a fixed fee.
The internal doors inside(x2,one for notes and one for change) both were a form of chip board and required 2 keys,but the exterior were a pretty sturdy piece of kit.
I hope you find a solution.