I should have known, the cooling down and preheating, did make the Prusa work nicely but the model started to come lose from the hotbed. So I had to trerminate the print.

I recall that there was a "change filament" option in the Prusa many but can't seem to find it. 

So I had no other chance then to pause the print, move the extruder sideways, unloaded the filament and load the new filament. When I pressed the Resume print, the printer continued where it left off. 

Now I am doing a second experiment, pause the print, and make the hotbed and extruder cool down. The plan is to see if I just can preheat it tomorrow and continue where I stopped the print. 

This would solve my 19 hour print, I can spread it across days.

Testing a new model on my 3D printer. This model is destined to fail but I want to see how big my Prusa can print and see what happens when I change a filament during printing. Can the Prusa continue the print like nothing happened or will I need a restart?

Stopping a print and start a new one from a certain layer won't work on the Prusa because it wants to recalibrate and there is a model alreadfy blocking the hotbed.

It is unclear why the temperature dropped but chance is that it was a bug in the gcode. Recreated the model and it now prints perfectly.

Started printing parts of the Thor robot parts but suddenly the heater starts to cool down. Aborting the print.

Contact spray did not resolve the bad contacts on the thermal header temperature sensor connnector.  You get a thermal runaway caused by the bad contacts and therefore uncontrollable temperature. The printer detects this and decided to stop the print.

So after 3 trials, I got fed up with it and soldered the contacts.

A big fat warning! It is harder than you would expect. The 2 wires are very thin and you almost can't expose the wire. The wire protection material is hard to get rid off.

Make sure that you have electrical shrink-wrap so you can bind the sensitive wiring after the soldering. If you don't, the wires will break.

All my projects are being build using this Original Prussa I3 MK2. I adore this printer, it came in a self assemble package.

The assembly took longer than expected: 12 hours.

When I assembled it, I thought it would be easier, but even with the very
nice assembling guide, I had to use my own brain to get it right.

The biggest issue I have is the thermal head temperature sensor. Initially
it told me that is was only 14 degree and refuse to operate. In the end
it turned out to be a lose connection.
This thermal connector
still gives me head-aches, it appears that it does have bad contacts
causing the temperature measured to jump. I now cleaned it with a
contact cleaning spray. So far so good.