Hi Dan, with the guitar should’ve come some Alan keys. Take the smallest Allen key there, and at the back of the tremolo arm “socket” on the bridge (the fine tuner side), is a small screw you can insert the Alan key into and this will tighten into the arm. This then holds the tremolo arm more firmly in place.
Let me know if this helps!
Also, please post some photos or a video of your new custom!
I’d love to see it before I get one myself