Thought i might take the bonty out for a spin but discovered that one of the pistons had seized. I have got it moving but in doing so i have lost a lot of brake fluid. I have Shimano and Magura mineral oils so i should have enough to refill the hoses. But how is it done?

There is a bleed port on the lever and on the caliper, and you screw a tube into each of them, then force fluid from the caliper up to the lever until no bubbles remain.

I’ve not had Maguras for years so I’m unsure of the thread of the bleed port or whether something could be bodged for it.

Sounds like i might need to get a syringe to force the fluid through. I know where the port on the caliper is, not so sure about on the lever but i can guess.

I remember on my old trials bike I used a single magura syringe screwed into the brake caliper, with the screw untightened from the lever. Keep pushing in the oil until there are no more bubbles coming out of the lever (I think you need to tilt it as well so bubbles are not trapped). There should be quite a few guides on the net.

“bleeding HS33”

EDIT::

On my old HS33 (about 5 years ago) the oil came out of a small screw right next to where the hose connected to the brake lever. It might be different to new ones.

you might be able to bodge it using a wide syringe and some kind of seal on the caliper end. Air won’t enter the caliper when you’re forcing fluid in as long as you can get an airtight seal, then once you tighten the screw at the lever end you can just remove this seal and close it up again at the caliper.

For some reason gaffer tape seems like a good idea to me.

bodged it using a small bottle of Shimano mineral oil and wedging it in the hole.