A couple of the spokes where gone on my Bakfiets. I tried all the bike shops in Oxford and none of them stocked the right size. Bakfiets bikes use especially thick spokes (2.5mm). The previous owner had replaced the broken spokes with thin spokes and these were essentially useless they could not take the load.
It turns out that the Bakfiets essentially use motorbike / moped bike spokes. You can order custom spokes in batches of 10 from a company called Central Wheel. They sound around £2 per spoke. My bakfiets wheel was a little a small buckle and I didn’t feel confident in replacing the spokes myself and so in the end I took off the wheel and got it rebuilt by Your Spokes. He measured and ordered the correct spokes from Central Wheel.
You can see how thick the spokes are and also a missing one.
Out of interest, I took the wheel off by resting the bike on an old railway sleeper and tied it to a bin to keep it upright. I’ve also taken the box off because I’m remaking it at the moment.
Hope this is helpful for someone.