What's happening with the SMU200s?

Good question. So let's go over.
The SMU200s were introduced in the mid 1990s to increase capacity and continue the removal of diesel hauled services, however, they have been plagued with unreliability issues.
Here is a photo of  an SMU 200.

This is the current look for the SMU200s, with the new QR logo and a fresh paint job. These units have undergone refurbishment from QR to update them to modern standards. Unfortunately, these units suffered from reliability issues from the start. While testing on the Kippa-Ring line, SMU203 suffered a breakdown, and was been taken out of service and stored at Mayne. SMU 210, 211 and 212 have also been pulled from service. The units are turning 21 years old in 2017, which means it is time for a major overhaul, or as QR are talking, retirement! Hopefully they will be refurbished, possibly next year or the year after, while the NGRs are entering service.