One of the persistent problems with BTE aids is keeping those plastic tubes that connect the BTE to the ear mold supple, clean, and free of cracks. So I have a supply of tubes which I replace every 6 months or so. I have found tubes for sale on ebay that you can buy in bulk to do this. I have had a few problems, however, gluing the plastic tubes into soft molds which I now use (soft is best for feedback suppression and tight fit). Soft earmolds really do not hold the new tubes in very well-they need to be glued in. If I replace without glue I will risk losing the hearing aid. But I have found that liquid super-glue works, the stuff that is sold in dollar stores with lots of cautions on the label and that hardens instantly. My dollar store has two kinds: gel and liquid. You want to use the liquid, and put just a drop or two way up on the shaft that goes into the earmold. This solved a little home-repair problem for me very well.
With soft molds, you should get tubing with tube locks (either a plastic or metal ring around the tubing that helps lock it in place).
Thank you for this tip. I will ask my audiologist for them.