The TSL 6.4 GHz ECR ion source performs reliably and is well optimized for the various ion species that are routinely provided for experiments. Beam intensities are comparable with other similar sources but at the lower end of the spectrum. We are thus investigating a number of methods of improvement. The development of a micro-oven for low melting point materials was successfully concluded. Further development is needed to improve the consumption rate in order to enable more effective use of expensive isotopes. Measurements with operation of the source in the after-glow mode were successful but the pulse to pulse reproducibility should be further improved. Although the maximum gain compared to the CW mode is satisfactory, accomplishing a higher factor would be even more advantageous for beams delivered to CELSIUS. A systematic study of various parameters was started in order to find optimal operating conditions running in the after-glow mode.