Found the problem to be the springs. The EBC clutch kit springs are the correct od and length however the spring wire diameter is larger so that when the spring bolts are torqued there is no room to compress.
Did you offset the last clutch disk? That is the last disk in the basket does not run in the slots like all the others but sits on the end of the fingers of the basket.
If the part from EBC is incorrect, notification of the vendor and a request for replacement or refund seems reasonable, to me. Almost every company occasionally makes mistakes at times; denying the manufacturer/seller the opportunity for corrective action only insures future identical mistakes, IMHO.
An Internet-led boycott doesn't appear to me an efficient, or even an effective, agent of change, YMMV.
EBC isn't infallible, by any means. EBC brake shoes for a rear KLR250 hub were too wide at the pivot eyes to release; in this case, my dealer's service manager and Mr. Bench Grinder corrected the problem. I left notification of EBC up to the dealership; would have done it myself if I had purchased directly.
New shoes at top were too wide; left insufficient clearance within hub for free expansion and contraction inside brake drum. Old OEM shoes, shown installed at bottom, were correct width. Mr. Bench Grinder customized new EBC shoes:
DISCLAIMER: My dearest friends and truest critics might suggest this post is off-topic. They may be correct! If so, deepest regrets. My rationale: The GENERAL discussion involved defective parts from a vendor/manufacturer, in the previous and current case, EBC; and . . . possible resolutions/countermeasures to such situations. Thus, I thought my utterance might be accepted, at least . . . tolerated!