In a midday research note, analyst Steven Fortuna said information from the company's Taiwan analyst suggests that production levels for February will be somewhere between 5,000 and 10,000 units, similar to the 5,000 units it estimates were produced in January.
"Our forecast for the (current) quarter calls for 200,000 units, which would mean a lot of units need to be produced in March," Fortuna said.
Apple's shares fell $1.65, or about 7 percent, to close at $22.02 on Wednesday.
Fortuna said the numbers show Apple could have trouble meeting earnings estimates for the current quarter, which ends in March.
"We are hearing that there could be some radiation problem with the product, which we think could partially be the reason for manufacturing issues," he said.
An Apple representative declined to comment on the report. The company, however, has said it expects demand to exceed supply this quarter, and it will increase production over the course of the quarter.
Analysts and retailer Amazon.com have said there isdemand for the new iMac, which was by Apple Chief Executive Steve Jobs in January.
Apple itself said in late January that it has received 150,000 preorders for the machine, the most for any new Apple product. The company said in its quarterly earningsin January that it budgeted to ship products from Taiwan by air all quarter in an attempt to meet strong demand.