The E85 is quite an old model now and a long time since Ive seen one.
It it has a dedicated, separate *programming mode* that you can get into from the keyboard, there will probably be a function for setting the brew temp up or down.
If it doesnt have a dedicated programming mode for you to get into, then it probably doesnt have a way of resetting the brew temp.
In any case if it were possible, it would be in the booklet. The booklets are quite good.
If the booklet doesnt indicate that there is a programming mode that you can get into, then you probably cant reset the brew temp.
The model may have been in the last wave of models before the electronics were upgraded to incoude a programming mode.
That said, you could try contacting another site sponsor (or ex sponsor?) Gilkatho in Brisbane and if they have a better recollection than I they may be able to advise. There is a dedicated authorised Jura service centre in each capital city, and I dont believe anyone would ask you to bring the machine in for "service" if they knew for certain whether there is a brew heat programming function or not ie i believe you have spoken to people that dont know or cant remember ( a bit like me) ...because the model is long gone.
As in, do not discount that what some young sales or tech person has told you will certainly be relevant to todays models, but not necessarily to models they may never have seen and are unfamiliar with (and didnt even know existed)......the technology now incorporated in the better auto machines has gone virtually into the space age compared to how they used to be and there have been several model revisions since the E series which was one of the best machines of its time.
Sorry cant be more help.
The other part of my reply is:
It is quite possible there is nothing wrong with your machine at all and thats just they way they were......however I dont consider placing coffee ina microwave to be "normal". I ALWAYS prewarmed my cups when using such machines, by just running water into them from the steam / hot water spout, and that should do.
But the only way you will find out is by taking it in and getting someone to look it over I guess.
Hope that helps a little.