AMF,
Traction tires have a life. They dry out whether you run the trains or you don't.
Rechargeable batteries will only hold a charge for a period of time, then they go flat. The old MTH 8.4 volt NiCad batteries in the original PS2 engines will lose about 20% of their charge for every month that they aren't charged.
The above are "natural laws".
The speakers in 5 volt PS2 engines are a different story. They should last the life of the engine, however, those MTH used were, unfortunately, defective. The replacements that MTH sells are not defective.
There's always a risk when purchasing something and not determining that it works properly during its warranty period. In your case, neither the traction tires nor the speaker would likely have failed during the warranty period. Further, traction tires are considered maintenance items and aren't covered by MTH's warranty.
Consider yourself lucky that you didn't encounter any truly expensive issues with your long-stored engines.
