Chain Saw PCS2200. Replacement SDS assembly required?

Performance Power Chain Saw PCS 2200

My chainsaw has the SDS Tool Free system which consists of an outer ring - which adjusts the tension of the chain - and an inner screw which adjusts the tension of the chain bar.

My inner screw assembly has broken. Any ideas where I can obtain a replacement part? It may be that I would have to buy the inner and outer components as an assembly. Any advice appreciated. Thanks