If you know the supply current, you can estimate what the ripple voltage is expected to be and get an idea of whether the capacitors are drastically degraded or not. Or many multi-meters include a capacitance measurement capability, you can measure using that taking some care about other devices connected that might disrupt the measurement.
The formula is Vr=I/2pifC
From the schematic it appears that C=1000u, f=100Hz, and according to post #33 the current is around 0.760A.
Vr=0.760/2*3.14*100*0.001=1.2V
Actually there is a comment later which indicates that some transformer under discussion could run 4 units, but not clear if that refers to the transformer rated for 0.760A, or a different larger transformer. I read all of the old comments and never found a comment which confirmed the current consumption of a working unit.
So it would appear that either your unit is drawing more current than expected, or more likely the capacitors are at least down to half the capacitance they should be.
With new capacitors the voltage will probably be just barely OK, but assuming that your AC line voltage was close to nominal, it is possible it could still get noisy when the AC line voltage drops (e.g. on a really hot day if you live where every building has air conditioning, or a really cold day if electric heaters are common in your area).
It never hurts to have heatsinks on regulators, so I would consider adding heatsinks on those.
