Don’t stop at checking for active leaks. It’s important to proactively inspect the condition of the plumbing arterial system to check for possible future leaks.  Brittle hoses and pipes are more likely to spring leaks down the road, and fragile plumbing can easily be damaged by the stress/flex when a hot tub is moved.  

Tips:

-Check the glue used at the unions and joints – is it appropriately firm, or is it dried and brittle or is it too soft and gummy?
-Check the hose clamps – if metal, are they rusted out?  If plastic, are they cracked or brittle?
-Check the flex lines by moving them back and forth.  The should be supple and pliable, and not stiff with age.
-Check the outside surface of curved ribbed flexible pipes for fissures.  The inside surface of a curved pipe is compressed while the outside surface is stretched taut, and as the pipes get older and dehydrate, they sometimes form hairline cracks which grow until water begins to weep through them. 
-Check the clear tubing – is it still transparent or has it yellowed or become opaque?