Whether the dissipated electrolyte can be seen or not (it is usually not seen), it is a fact that heat slowly degrades and dissipates the fluid over time. This occurs more rapidly on smaller sized capacitors, of course. And keep in mind that a capacitor may give a correct capacitance reading and still fail in-circuit due to its increased ESR rating. ESR speaks of the "resistance" rating of the capacitor in series while in the circuit. ESR Meters exist to test this value, even while the capacitor is in-circuit. An extremely high ESR value could cause the capacitor to rupture at some point.
Suffice it to say, whether you see the aging effects or not, you should replace all the capacitors, including the big electrolytics. It's been about 20 years on a lot of these compact Macs, folks. It's time to change those caps. (And yes, there are such caps even on the 128k logic board too!) With regard to the SE/30, the kit I purchased from Trag (at a very economical price) included both axial caps on the logic board. I did the job myself, but some on our last such as phreakout offer to do the job for a nominal fee. Unless you are skilled at the job, it would be worth it to pay to have the job done professionally. And it's not like you have to do this every few years. Once the main SMD caps are swapped out for tantalum versions, there will be a relative few fluid filled caps. And since those fluid filled caps are all the large sizes, I doubt you will need to swap them out again for at least another 15-20 years. Perhaps by then, assuming you are still around then, there will be a non fluid-filled version available to replace them.
Lastly, I agree with Mac128. I think the Classic's plastic case is a bit more spiffy than the SE and SE/30 series, but except for that, the SE/30 is better all around.
Suffice it to say, whether you see the aging effects or not, you should replace all the capacitors, including the big electrolytics. It's been about 20 years on a lot of these compact Macs, folks. It's time to change those caps. (And yes, there are such caps even on the 128k logic board too!) With regard to the SE/30, the kit I purchased from Trag (at a very economical price) included both axial caps on the logic board. I did the job myself, but some on our last such as phreakout offer to do the job for a nominal fee. Unless you are skilled at the job, it would be worth it to pay to have the job done professionally. And it's not like you have to do this every few years. Once the main SMD caps are swapped out for tantalum versions, there will be a relative few fluid filled caps. And since those fluid filled caps are all the large sizes, I doubt you will need to swap them out again for at least another 15-20 years. Perhaps by then, assuming you are still around then, there will be a non fluid-filled version available to replace them.
Lastly, I agree with Mac128. I think the Classic's plastic case is a bit more spiffy than the SE and SE/30 series, but except for that, the SE/30 is better all around.