I ordered in eight different products that were listed on Amazon that might be possible replacements for the "Space Bar Stabilizer" that is out of stock at Mouser. It isn't the cheapest one at $14USD, but it is available with Prime shipping and appears to be have plenty in stock. Other sets that I ordered have much slower delivery times but better pricing at around $8USD. I'll post an update when they arrive. The installation of these stabilizer parts is kind of unintuitive, so I'll post some installing instructions and pictures later...