Having 13 Omega D5-XL's to maintain, parts can be troublesome to find -- even though the enlarger is still in production. A call to the main supplier of Omega parts told me that the counterbalance springs are not in stock, and Omega does not know when they will be available. The supplier did have a couple of the counterbalances that have been refurbished for $99 each.
At this price, one might as well buy a used enlarger for $100 and save that much again by stripping it of the parts.
I contacted the Pullman Manufacturing Corp in Rochester, NY, and they made me a couple of the counterbalances for $65 each (and I have ordered 4 more to have on hand). The counterbalances installed and work perfectly. So if you need one or more, you can contact them. It is not on their website, but they'll know what you are talking about.
email@example.com or call customer service at 585-334-1350 x302.