To unclog a hose Electrolux® Corporation (now Aerus LLC) suggested attaching it to the exhaust port and inserting the open end into the suction port. If that doesn't work then dislodge or loosen the debris with a dowel and repeat.
You will likely need a new hose anyway if it is a braided one. The newer version that Aerus makes is vinyl. Cheaper aftermarket versions (in terms of cost and quality) are also available. Leaking hoses diminish the suction level. Braided hoses, though, may be resealed using a product called Rubber Dip Spray® by Plasti Dip International--it's just more time consuming. Do a Vacuumland search using that term and 'hose repair' to locate a thread with detailed instructions.
Another item to check for blockage would be the power nozzle's head and wand. Check to see if your brush roll needs replacing, as well.
Yes, a full or nearly full bag or one containing fine dust or powder would also diminish your cleaner's air flow. Be sure to use genuine Home™ Solutions bags available online from Aerus LLC or from an Aerus franchise (or if your grandmother has genuine Electrolux®, Germ Grabber™, or Sure Thing™ bags they would be fine, too. All others are cheaper imitations which are more prone to leaking and even bursting).
Cleaning a motor's dust- or dirt-laden fans is another way to improve your cleaner's performance.
It's great that you will be keeping your grandmother's vacuum cleaner and using it. The Model G is one of Aerus's best all-time machines. Best wishes in restoring its performance.
