If you need to hacksaw through a fastened pipe or rod, but the space above is cramped, try this: Remove the hacksaw's blade, straddle the pipe with its frame from below, then reinstall the blade upside down. The teeth of the saw will cut through the pipe from the opposite side. In many cases this trick will allow you to complete a cut that would be otherwise impossible.
Several methods are available for dealing with screws that tend to vibrate loose on covers of equipment such as chainsaws. One good fix is to remove the offending screws and wrap 1/2-in.-wide Teflon tape around the threads and then screw them back in. The tape will hold the screws tight, yet will allow you to remove them when necessary.