Power Plant Premier - unused for long time

Hi all,
My Power Plant Premier has not been used (in storage) for a few years. I am terrified to power it on as I already had a problem with a power amp that has not been used for long time (protection light stays ON permanently when started).
A friend of mine suggested that in this case the unit should be started at lower voltage than the standard 230 V (I’m in EU) and then gradually increased, however I do not have such a device (“autoformer”?) to do that.
Any suggestions/advice would be highly appreciated.
Peter P