An Accenta is a budget system so you get what you pay for. This is irrelevant to the advice for having the system serviced.
If you don't have some technical knowledge you are not going to be able to locate the tamper in the first place, the tamper fault could be any component in the system.
While your fix may work, possibly better than the original design, it looks pants. There is no way you can justify this type of fix for a paying customer. Any installer would rip the panel out and fit something decent if it was there own system.