I couldn't say specifically but I know Swallow Amusements do MTC 9000 flybacks, they might do 900 as well (try emailing them if not listed on their site as they do a lot of hantarex repairs)
I know that there are a few differences between the 900/E but I'm not sure if the flyback is one of them will have to wait for someone more knowledgeable on that model to chime in, however I wouldn't bet on them being the same worth looking for a MTC 900 one

A guide to discharging? Well there's quite a lot about it in the 'Monitor FAQ' up top. Basically, you get a long screwdriver, 2 alligator clips, clip one end onto the metal shielding going around the front of the tube, clip the other end onto your screwdriver. Then gently slide it in under the anode cap and it will discharge. Make sure you aren't holding onto anything metal, that the alligator clip is far away from your hand etc. and use your right arm to hold it so if it does bite you it won't go through your heart (but if you follow that/common sense and keep away from the metal then it won't anyway).
By no means a thorough guide but if you read the monitor faq sticky there's some more in there. This is what I've always done and it's always worked just fine for me
