mx5cartalk.com

Sounds like you have the infamous 'slider pin' issue. The slider pins will corrode if regular maintenance is not undertaken. Here is a previous post on this very subject.

viewtopic.php?f=30&t=42278

and

http://www.miata.net/garage/ebrake/index.html

and

http://forum.miata.net/vb/search.php?searchid=4843116

J.

if it persists after greasing the slider pins then probably the pistons slightly corroded in the caliper.

i had that a few months ago, the slider pin was a bit ugly but also the piston was siezed on..mania had brand new genuine ones for half what i paid for a recondition,
if only i had known at the time