This Fire Truck is very expensive but an amazing toy that will keep your child and neighbors kids occupied for hours! It even comes with spare parts found on the Bruder Service site, here , and service repair videos here.
Unfortunately, even though there is a video showing how to replace the black ladder string here, the Bruder Service website doesn't sell a replacement string, but rather wants the customer to purchase the entire ladder for about $20.
The ladder comes in three sections, top, middle and bottom. The top ladder is attached to the string by a silicone ball that is firmly attached to the string and snapped into the ladder. In the Bruder instruction video, it is the first thing that is disassembled when replacing the string.
My instructable shows how to fix the ladder with a piece of fishing line/jewelry line when this silicone ball gets ripped off by your neighbors kid or starts to slide on the string [my kid would never ruin a toy :-)].
Step 1: Placement
The first thing you need to do is find the correct placement of the sting.
1. Take off the top ladder.
2. Take 1 yard of fishing line/jewelry line. It should be thin so that you can make a fine, firm knot and not a thick line that would be used when deep sea fishing.
3. Loop the fishing line behind the black string on the middle ladder and then thread both ends into the whole where the ball is supposed to go.
4. Replace the top ladder into the middle ladder while keeping the fishing line in place.
5. Make one firm knot in the fishing line, which places the fishing line around the black ladder string.
6. Remove the top ladder and take out the fishing line from the ladder. You should have the fishing line attached at the correct location on the black ladder sting.
Step 2: Make Multiple Knots
With that one firm knot in place, you can now add extra knots to keep the fishing line firmly attached to the black ladder string.
1. We want the fishing line to be attached around the black ladder string, so loop one end of the fishing line around the back of the string and knot. DO NOT simply knot the two strings one on top of the other, but LOOP around the black sting and then knot.
2. Repeat 2 times above and and 2 times below the original knot.
3. Test that your knot to see that it doesn't move along the string by pulling up on the fishing line and down on the fishing line several times. This imitates a child playing by yanking up and down on the ladder.
If your knot is good move on to the next step. If knot is not good, CAREFULLY cut away the knots from the string with a box cutter knife and start over.
Step 3: Tie Down the Top Ladder
After the knots are in place we want to attach the ladder.
1. Thread the fishing line through the hole of the top ladder.
2. Thread each end of the line through the gaps in the ladder adjacent to the hole (above and below and maybe crisscross). DO NOT KNOT and NOT too many times. [I feel like this is a DR Seuss Instructable :-) ]
3. Replace the top ladder into the middle ladder and tighten your fishing line.
Step 4: Test and Final Knot
1. Test that the assembly works by pulling up on the fishing line.
Your top ladder should be working correctly and moving simultaneously with the middle ladder like they did when you first un-boxed the toy.
2. Make a few knots to tie down the fishing line to the top ladder and cut away the remaining fishing line.
All Done !