2 pointsThose ultra small size capacitors were produced by Japan manufacturer HITACHI, in limited quantities, by special orders of Inon and Sea&Sea. This is HD6 family of capacitors, it has always been in short supply due to a rare type of very rough foil inside. They are unavailable on casual open market of capacitors. Of course, Inon can replace the capacitors together with the main electronic board in the service center, but it is not cheap including delivery costs. Chris Ross already have written above, that problem may be not only in capacitors but also in the main electronic board. A year ago the spare PCB for Z240 was available, even including eBay, but currently product is totally discontinued. It may be available only in Inon service center. But officially, that spare PCB is discontinued. The good way for repairing Z240 now can be in purchasing a damaged Z240, disassembling it for spare parts. Sometimes i used to buy it very cheap. Many people have them on hands, because this model was in production so many years.
1 pointYou can use the filter with WWL-1. The magic filter can sit inside the lens or you can use the Keldan red filter for WWL-1 which is about twice as expensive. If you choose to use strobes or other lighting source (including the sun, shooting close to the surface), it makes things more difficult. Edited: Just did some more reading (https://www.uwphotographyguide.com/underwater-photography-filters). It looks like the filters only help in a fairly narrow depth range where you have enough red, but too much blue/green. Beyond that, you would need a light source or live with blue photos
1 pointThat might be a good idea. Alex Mustard might have a thought on that. ;-) I used a magic filter for a while, several years ago, and it definitely could make a difference in ambient light pictures but if I recall correctly, its effect varied a fair bit depending on the direction of the ambient light. I suspect it could help with photos like these. It would be a fairly inexpensive experiment at the worst.