The arm has been replaced and seems to be strong enough. A new piece of thin rectangular steel was cut, and reinforced via a smaller, but thicker, piece of steel placed inside it.
The arm also has 3 solid guy wires instead of rope. The tower that supports the guy wires has been lengthened for better leverage. The counter-balance for the arm was moved outward to account for the heavier arm.
For smaller catapults, I like making slings out of duct tape- it’s easy to make and relatively strong. But they are prone to tearing and can be bulky (especially after being repaired). This was a problem with Drill Sergeant, but I think I’ve come up with a good solution.
A combination of Tuck Tape (a strong polypropylene sheathing tape) and duct tape makes for a very strong, lightweight and flexible sling material. Wrapping the Tuck Tape sticky-side-out around a piece of drain pipe gives the perfect shape / size, which is then covered with duct tape (sticky side in).
A small wire frame is then taped on. The sling lines tie onto the frame. That way, if the sling needs to be replaced, all you need to do is cut the tape off the wire frame and tape on a new one. Even if the new sling had to be made from scratch, the whole replacement process would take less than ten minutes- useful in a competition scenario!
It looks like the arm couldn’t handle MORE POWER (*Tim Taylor grunt*).
So, that will need to be replaced. Fortunately, everything else seems to work relatively reliably.