Unfortunately no photos, as I didn't really expect it to work to be honest, it was just one last shot out of exasperation. I left the site and the machine did a good whole day's work, and now its started acting up again. I cant even go back as they've banned inter city travel here cos of the virus. I did however manage to get hold of a complete tank off of a scrapped 955L. It's plumbed for a ripper and multi purpose bucket as well, which mine doesn't have. So the plan is to blank off the outlet ports for the accessories and send the entire tank to site to be fitted (if I can get a lorry through the lockdown roadblocks). Hopefully this sorts out the issue, and once the machine comes back to the yard, I'll bolt on a ripper and fabricate a multi purpose bucket out of an old dozer blade I have. I think the jamming must be due to wear, although I can't say it felt sloppy in the bore. I've asked the Mechanic on site to try and free it up again, so that way at least we'll get a bit more work out of the machine before I can get the replacement tank to site. Btw Mantrac quoted me $3200 + 1 month waiting time for a new relief valve.