FAEMA C85 S/1 Where to start?

[Flo Baine]

Hello!

Really glad I found this group, thanks for any help in advance.

I just got this FAEMA and would like to ask you guys for some advice.

I want to restore it to former glory by giving it the neccesary TLC. Here are some facts/questions. 

The owner mentioned that it leaks but I dont know where..

I never saw it running so i cant really tell if it does.

I was out of use for a couple of years

The previous owner had it serviced regular and handed me the manual including invoices for services and spares.

Facts.

The power light comes on when i switch it on(i just switched it on fo a minute)

The heating element works(boiler is getting warm)

That manual filling button is super stuck, doesnt move a millimeter.

The water gauge is filled with a lot of sand see photo

The pressure gauge seems to be stuck 3,5 bar

The leak could be at the back of the heating element, there is a lot of residue

Questions:

1. Is it possible to run it from a tank/bottle DIY setup? I think I read somewhere that it is possible for this machine but please correct me if im wrong.

2. For testing purposes in the garage i thought of connecting it to  a 2 liter bottle/jug  on top of it. Drill a hole in the bottle cap and connect it with hose  to the water inlet. Stupid? Impossible? Good Idea?

I thought i would try just getting it to work without doing any major cleaning first.

That way i could see if it works. Maybe it is beyond repair?!? That way I might save some unneccesary work( Thats whay I bought an old espresso machine , to save unneccesary work  :) )

How would you guys proceed?

Short Term plan:

Get it running and see if it works, and what doesnt work, especially the aforementionded leak.

Long term plan:

Take  it all apart clean and reassemble.

Thanks Flo