I do electric shutters not manual, but the standards for mechanical aspects are the same (BSEN12604), just doesnt then need BSEN12453 for the electrics side usually on a service youd be looking for any issues with it, give it a bit spray etc, they dont really take much doing although id expect they would have at least had a look behind any covers at the top, check the condition of the chain etc, make sure spring is balanced (obvious by taking it up & down) current standards require that it cant fall in even on a failure of a single part. in electric that usually means a brake on non motor side, however manual shutters have the spring that side so really any single failure and its not likely to suddenly drop excessively