Apple (AAPL) and J.C. Penney stores have something in common -- leadership in turmoil.

Apple stores have lacked a steady leader since former retail chief Ron Johnson left in 2011 to take the reins at J.C. Penney. He was ousted Monday after his efforts to transform the struggling department store proved a colossal -- and costly -- failure.

Apple isn't suffering like J.C. Penney, but experts say the Cupertino tech giant could start to lose its brand power and sales numbers if CEO Tim Cook doesn't soon find the right leader for its snazzy and wildly profitable retail stores. Without steady leadership in almost two years, Apple stores have been left to stagnate, employee morale is sinking and customers are getting bored with the same-old store experience, analysts say.

"The stores have been kind of in cruise control since Johnson leaving, and (Apple founder Steve) Jobs dying," said Roger Kay, president of Massachusetts-based Endpoint Technologies Associates. "That can't be great, because retail keeps moving. If you advance the clocks just a few more ticks, Apple suddenly looks dated."

Apple's 402 stores are far from broken. They have become a consumer destination that spurs interest and intrigue. They give customers a sense of intimacy with the company that they can't get ordering an iPhone online, and give Apple a leg up on competitors like Samsung and Amazon. Last year, average revenue per store increased to $51.5 million compared to $43.3 million in 2011.

But they have changed little since Johnson whipped up the retail model years ago. Already, there are some signs that customers may be bored; lines outside some stores for the release of the iPad mini and fourth-generation iPad were shorter, with many customers preferring to order online.

"The problem with the consumers is they expect everything from you," said Robert Passikoff, branding expert and founder and president of Brand Keys. "And expectations only continue to grow."

Passikoff gives Apple about 18 months before the leadership vacuum starts to hurt retail sales. A retail chief is necessary to give employees a sense of stability and direction, and to figure out a new look for the stores to showcase Apple's newest products in ways that continue to entertain and intrigue customers.

"Cook needs to hire someone who has the finger on the pulse of the consumer and provide the kind of service to meet their expectations -- and do it before anybody else," he said.

Other tech giants have followed with storefronts of their own. Microsoft has expanded its retail footprint, placing a store in nearly every shopping center or mall where Apple has a presence. Google (GOOG), too, is rumored to be planning a string of Apple-like retail stores this year to let customers try out gadgets like Google Glass.

John Browett, Cook's first high-profile hire as CEO, lasted less than a year as Johnson's replacement. He was given the boot in October, but not after causing a backlash for his plans to cut staff, accelerate performance reviews, reduce promotions and overtime, and change work schedules, according to some staff and other reports. Morale has been in the dumps since, and store staff need a new leader to get them back on track, said Cory Moll, a specialist in Apple's downtown San Francisco store who led unsuccessful efforts to create the Apple Retail Workers Union.

"It definitely felt like there was a vacuum when John's departure was announced," said Moll, whose last day as an Apple employee was Tuesday. "It made us all feel like, 'Okay, who is leading this ship right now?' A lot of us were eager to see who was going to fill that spot."

But instead of getting a new retail chief, store employees lost a second leader earlier this year when vice president of retail Jerry McDougal, who many expected would be tapped to replace Browett, resigned. An Apple spokeswoman said the search for Browett's replacement continues. She would not comment on speculation about Johnson's possible return to Apple.

The success of Apple stores is largely due to the people who staff it -- personable, highly knowledgeable and well-trained to bend over backward for customers. In many stores, the employees on the floor often outnumber the customers so shoppers get a one-to-one experience. The longer the retail chief position remains vacant, the longer employee morale, the very engine of the stores, is at risk of crumbling, analysts said.

"The damage for the moment probably can be remedied fairly easily, but they shouldn't let it fester for too long," Kay said. "They need to get the right guy in place to take the reins firmly."

Contact Heather Somerville at 925-977-8418. Follow her at Twitter.com/heathersomervil.