Inner Pen Cap question -- shellac or sealant?

[Bunk2019]

My husband has a brand new Levenger carbon fiber pen that has an inner cap and cap band problem; they have both separated from the cap and from each other. The pen is discontinued and Levenger doesn't currently have a replacement so he can't send it back. The inner cap and cap band have adhesive residue on them so they weren't just pressure fit when they were installed. I've been reading about shellac and thread sealant but can't decide which would be the best choice for the repair and can't find anything about inner caps being shellaced/sealed in place. Everything I've read so far indicates that most inner caps are pressure fit. I think that the repair should be permanent so am leaning toward shellac but I can see why you might want to dismantle the cap for cleaning in the distant future so maybe sealant is a better choice? Does anyone have any thoughts or advice?

D9E07E7B-BFC1-4894-96E4-9E77E099BB8E.jpeg
58306987-D679-4F8D-BE99-8465A4F74BC7.jpeg