At a recent hearing Nottingham city council admitted fault when one of their workers suffered hand injuries. According to healthandsafetyatwork.com one of their employees was trying to unclog a lawn mower when his right index finger was severed and other fingers on his hand were damaged.
During an investigation the HSE found that safety guards were routinely removed by council staff in order to access blockages more readily. This was against the recommendations of the manufacturers. In short, a flared guard that covered ejected clippings was replaced by a simple hinged gate much closer to the rotating blade. Granted you had to have the blade rotating in order to get any serious injury.
The council was fined £33,000 with an order to pay £12,000 costs. They were also criticised for failing to supervise apprentices and failing to properly train people in using the lawnmowers.
There are pictures of the modification but I am not sure of the permission to use issue. Below is the source reference. The lessons should be obvious. If you pick up a bit of kit that has been modified be suspicious. Never trust electric tape, duct tap, bolted on bits or empty bolt holes…ah, if it looks messed with leave it to the idiot that messed with it.