I have never found a lack of mirror lock-up to be a problem.
The problem with the shutter is that the grease gets old and sticky - and it does in most cameras. It is also very temperature dependent, being very thick in cold weather.
Rolf Dieter Baier will CLA the camera, re-grease it with synthetic grease (much more temperature stable) and can also fit a mirror lock up for an extra Euros 98.
Pentacon can also fit a MLU.
What part of the world are you in? If you are in Europe you have the Choice of Baier, Pracktika/Pentacon Service in Dresden or Tom Page in the UK, so buying a used camera on eBeeGeeBay and sending to them is an option to consider. That way you know just when and where it was CLA'ed and have some warranty...
Do have a look at TRA's site, especially the section "The Faulty Part".