Olivetti JP101 ink cartridges?

Since we are discussing obscure printer consumables... I have just bought an Olvetti JP101 on E-bay. This is the 'sparkjet' printer that was sold in the mid-1980s. It was commonly used over here with the BBC micro, and I beelive an Acorn-badged version existed. Mine has the Olivetti nameplate. One problem (and I knew this before bidding, I am not complaining) is that the ink cartridges for it are unobtainable. The machine came with a nearly-new one in it, and 2 brand new spares ,so I can at least try it out. But when i've used those up, nothing... The ink cartridge is a glass tube tapered to form a jet at the front end. It contains a solid ink with a compression spring [1] behind it which also acts as an eleectrical conenction to the rear metal end cap. Thetube is fitted in a little plastic holder. It clips into the printer carriage, an high voltage is applied between the ink (via the end cap and spring) and a metal paper guide. The resulting spark transfers some ink to the paper (note that the sparrk does not attempt to pass through the paper, and the paper is not special in any way. It's a pity the cartridges are unobtainalbe, since apart from the HV transformer module (which also contains at least one rectifier diode and maybe a limiting resisotr), the mains transformer (which is not likely to fail) and a programmed 2764 EPROM, all the other electornic compoents are standard (Z80 CPU, Z80 CTC, TTL chips, etc) and easy to get. The mechanism is pretty well made too, and looks easy to keep going. Does anyone have any suggestions as to how to make ink cartridges for this machine? -tony