We replace vacuum hoses every 5 years or so. And even then some of them show signs of deterioration. In a hot climate, parked outdoors, both hoses and gyros will suffer. In a cold climate, the fine oil in the gyro bearings will gel and get squeezed out, and the bearings run dry and wear out prematurely. We find that a heated hangar saves more than engines--it saves radios and instruments too.
The attitude indicator has a gyro wheel inside a case, and the case is gimballed so it can rotate in two axes within the instrument's outer case. Vacuum is applies to the outer case, and air is let into the aft gimbal bearing, where it travels through a hollow gimball frame into the inner case and spins the gyro wheel. It then leaves the wheel case through four tiny holes at the bottom, facing outward horizontally: one forward, one aft, one each left and right. Two pendulum valves hang from pins in the wheel case and are set up so that air is restricted or allowed free flow from each of those four hose. The purpose is to erect the gyro when it starts and to keep it erect; closing one hole will create a reaction from its opposite, and precession causes the wheel case to erect in the desired direction.
Now, if bits of rubber or rubber dust or the solids in tobacco smoke are allowed into the case, they will accumulate around and in those tiny jets and clog them. Clog one, and the gyro will go off level as the OP's has.
Dan