Many semi-auto feeding problems are magazine related, rather than gun related.
Frequently it's the shape or temper of the magazine's feed lips. Lubricated or not lubricated does not enter the picture.* Dirt inside the magazine is a killer, however.
The best diagnostic tool is two or three extra clean magazines. If at least one of them works reliably, it is indeed a magazine problem.
Some gunsmiths can re-shape some magazine feed lips, sometimes successfully. Most won't even want to try, especially in the case of arcane little guns like yours.
*You are not supposed to lubricate semi-auto magazines for two reasons:
First, because oil collects dirt, and dirt jams magazines. If your magazine is oily but clean, that's OK. If it's dirty inside, that's very much not OK. Look and see.
Second, because oil that has collected inside the magazine transfers that oil to the cartridges it holds. Oily cartridges can cause chamber pressures to rise, with catastrophic results. Oil may also enter the cartridge case, killing either the powder charge, the primer, or both.