Recovery of spectral energy resolution. (Top panel) Comparison of the observed and the trap corrected spectra extracted from WT observations of the Cas A SNR in October 2007. The fit of the Si-Kα line with an asymmetric Gaussian in IDL and a linear component to model the local continuum yielded FWHM = 159 ±    13   eV for the observed 2007 spectrum and 106 ±    3   eV for the corrected 2007 spectrum. For comparison, the FWHM value during an observation in February 2005 (shortly after launch) was 101 ±    3   eV. (Bottom panel) Results of trap mapping and corrections from PC mode observations of the Tycho SNR taken in October 2009. As radiation continues to damage the CCD the spectral resolution worsens, with a FWHM = 132 ±    3   eV after trap corrections in this case.