Looks like a 285 Coleman? These require a ‘sock’ style mantle rather than the more traditional round type mantle as the round mantles would interfere with the vapouriser / generator, I do use the round mantles for testing as they are generally far cheaper than the Coleman originals. The correct mantle would be a Coleman #21 string tie mantle, cheaper ones may be available but if they were genuine Coleman mantles I’d expect them to be around £2 each.
Top tip is run it on panel wipe, can’t remember which one but I’ll look into it for you. It is more expensive than petrol however it is chepaer than Coleman fuel, it burns brighter, whiter, doesn’t have the yellowish hue of petrol and as it is cleaner it doesn’t gunk up the generator, I had a ‘Mil-Spec Coleman’ at the pit and it burned as white as a paraffin lantern.
Another tip is don’t store fuel in it when not in use, the recommended is over a week as the tanks are steel on these and are prone to rusting on the inside if left with fuel over a long period, I normally empty them out and leave the fuel cap off the valve fully open when not in use for a while.
These shouldn’t really be called Tilley lanterns as Tilley is a seperate brand of lantern all together, however here in Blighty we seem to call all camping Lanterns ‘Tilleys’, which is a mahoosive PITA when people are buying spares from you and they have no clue of what they have - it’s a bit like all vacuum cleaners seem to be now known as hoovers.
these mantles still available?was given a lamp same as this a few years ago with a damaged mantle but never got around to fixing it.
Let me know which lamp you have, put some pictures up or soemthong like that and I’ll try and help you out.