leak in shower wall -- what to do?

[inafix]

I recently noticed that water pressure suddenly seemed low for our shower/bath. The shower backs to a linen cabinet, with a small access opening in the wall way down low (below the fixtures). So I stuck my hand in the hole and discovered water dripping, though only when the water is on.

I'm not sure what to do next. A plumber from our home warranty company said we'd have to remove the entire cabinet before they'd do anything. But it looks like I could pretty easily create a hole through the wall where the bath-level fixtures are. Up high near the shower head would be tougher.

Any advice would be greatly appreciated. (Beware I'm not very up in plumbing terminology.

[HayZee518]

the access hole is probably there for the line shutoff valves. look around with a mirror and a flashlight. you may be able to spot water leaking around the stem bonnet. there's a graphite packing in there. you may be able to tighten it with some channel lock pliers or a crescent wrench.

[pushkins]

Also, you can buy access panels in at least two sizes at Lowe's and Home Depot. So you could simply cut out a hole (to suit one of these panels) for the repair work to take place, once it's repaired cover in the hole with an access panel.