Situation: a shower that has not been used for several months; Delta Monitor 1400 Series single-control faucet; no water emerging from shower head when the faucet is turned on; faucet cartridge replaced; still no water; water is clearly reaching the faucet from the supply lines.
There must therefore presumably be some blockage in the riser between the faucet and the shower head, or in the outlet part of the faucet itself.(The problem is not in the shower head — no water comes out even when the head is removed.) What could this blockage be, and how to get at it without undoing the plumbing, which would mean taking the shower enclosure to bits? Poking with various lengths of wire has produced no result. Might a chemical approach work — something along the lines of Drano, or perhaps a mild acid to dissolve a possible mineral blockage?
[further message from original sender of question]:
Vinegar solved the problem. I unscrewed the shower arm half a turn, so that it faced upward, and then poured a few ounces of vinegar down the shower riser pipe. After about 3 days, it dissolved whatever — obviously some mineral deposit –was blocking the outlet from the faucet. Flow is now normal.