17 of the bars have two pegs, one on each side, only one bar has one peg, which is the last one to be placed on this puzzle ;)
No force is needed to assemble this puzzle, if you struggle to complete this puzzle on your own, no worries, here’s the solution to assemble and disassemble this slide puzzle.
https://youtu.be/em3O9yT8RsM?si=g692fva_GZL2D6Sy