Joseymack:
Many window unit air conditioners use the water to help remove heat from the condensor coils. They retain water in the outside cabinet, and the condensor fan actually has a "slinger" on it that picks up the water and tosses it on the coils, and the resulting evaporation with the air blowing through the coils helps remove more heat than it would if run dry. By using the water, designers can get by with smaller coils and fans, and the unit operates more efficiently, providing more cooling with less energy. There is also the added advantage of not having water running all over the place--it is just evaporated in the condensor air. I wouldn't be drilling holes and trying to help "drain" the water.
To the original problem, the only maintenance that you can really do to window units is to keep both the evaporator and condensor fans and coils clean, keep the filter clean, make sure the unit is mounted level, and that is about it. While any good shop can perform repairs on them, including evacuation and recharging of refrigerant, the labor cost can very quickly exceed the cost of a new unit--which will also likely be more efficient and quieter than the old unit.