Article for the Progress reboost notes and a bit of a ISS update:http://www.nasaspaceflight.com/2015/05/iss-enjoys-reboost-progress-m-26m-misbehaves/
The Station also has a set of thrusters on the Zvezda module can be employed. However, they are mainly reserved for when a Visiting Vehicle can’t conduct the task, as the requirement of protecting the Station’s propellant stores is paramount.
I thought the reason ISS tries not to use Zvezda engines is due to limited number of cycles they are designed for?
I try to find other reboost failures in ISS history. I've found one on November 29th, 2006 (Progress M-58's engines stopped because of ISS new configuration after STS-115).I'm pretty sure there was another case more recently, but I do not find it !!
Russian flight controllers identified an issue with one of the eight thrusters on the spacecraft that was disabled for Sunday’s backup attempt
Handhold Experiment Platform (HXP) Installation: Today, the JEM Airlock outer hatch was opened and slide table extended for the Small Fine Arm (SFA) to grapple the HXP and install on one of the handrails of the JEM Exposed Facility (JEF). The HXP is composed of several exposure experiments which will remain attached to the JEF for approximately one year, collecting data on material interactions to long duration space exposure.