Although a very resilient surface it is easily scratched and cracked if knocked or scraped with a sharp implement - be careful when handling it. It is actually strong enough to be cleaned with paint stripper and to show a great surface as long as it is not scratched, sanded or anything like. Other detergents may cause harm. If it is just dusty or dirty then normal washing up liquid will clean it. A good coat of beeswax will then keep it looking shiny.
These clocks have a very robust movement in them but they are mechanical and do require attention from time to time. A three yearly clean and oil would maintain it in tip-top condition. What tends to happen is that they will get harder to start as the oil dries out, until such time that they won't run at all. The self-starters just wont start at all. Unrepairable damage is more likely to occur to the earlier movements, so regular maintenance is the best way to preserve the clock.
Keeping the original movement is far less damaging to the original than having a quartz movement fitted and will give many more years of service in it's original form.
It retains the history and spirit in which the Smith's company took the clock market by storm in the 1930's until the 60's and if looked after will last more than a lifetime.
Some clocks from the 60's have plastic movement parts which are almost impossible to repair.
As a general rule; if it has a bakelite case it is repairable.
REPAIR AND OVERHAUL
SYNCHRONOUS WALL CLOCKS &
CONVERTING SYNCHRONOUS CLOCKS TO LOW VOLTAGE
ELECTRIC CLOCK CARE
ELECTRIC CLOCK MANUFACTURERS
STARTING A SYNCHRONOUS ELECTRIC CLOCK
BENEFITS OF A MAINS ELECTRIC CLOCK
SYNCHRONOUS CLOCK ACCURACY
ORIGINAL CLOCK INSTRUCTIONS