Back in the days of the tens of megabytes disks I knew of people who had opened and closed disks without problems, in a "normal" environment. Now I don't think anyone would even try.
In any case repairing the heads is impossible without specialized equipment. They cannot be taken out without disassembling the whole disk, and in the process of doing so you will touch and damage the surface of the platters with the heads. Also, removing the tiny screws holding the parts together will probably produce loose metal particles, unless you have the exact size and type of tool.