ZX Spectrums tend to suffer from two major problems. The earlier keyboard membranes were made from the finest Japanese rice paper and would shatter into a million pieces should a flea with a penchant for bean-based produce be within 100 miles of the area. More complicated are the electrolytic capacitors. These little beasties contain liquid-based magic smoke and as a result, over the course of 30 years or so, tend to go kaboom once they’ve dried out. The biggest issue with a capacitor failing is that it tends to kill whatever it was to which it was providing a stable current.
Many Speccy owners take the plunge of a pre-emptive fix. Replacing the caps before they fail to protect the components they serve. I have one Speccy+ that is my day-to-day machine and sees a lot more work than others. So, I took the plunge and replaced all 12 electrolytic capacitors.
De-soldering is a dark art and although I soldered my first circuit at about age 9, it’s only within the past year or so, at the tender age of 45, that I’ve really got the hang of removing components without destroying the circuit board. Turns out I should have been watching YouTube videos all along. The big secret is adding some solder before using the pump to clear the pads. The more solder, the easier it is to achieve suction.
So, my ZX Spectrum+ got a nice set of, frankly, better-produced caps and as a bonus, a good clean-up and a heatsink on the ULA (which was designed to run hotter than was really wise).
If you fancy having a go yourself, and improve the chances of your Speccy lasting another 30 years, I got a great value kit of capacitors (and bits for a composite mod) from https://www.retroleum.co.uk/zx-spectrum-capacitors.