Hi Irene. This is one of my favourite machines. This model uses a thermal printer, so there is no ink (it is in the paper).
If the paper is feeding out like it is printing, but comes out blank, there are two main reasons:
1. The paper is the wrong type. You need to use thermal paper. The way to test is to check both sides of the paper- one should be shiny and smooth, other side rougher. The other thing is to scratch across the paper quickly with a finger nail a few times and you should see black marks on the paper.
2. The paper is the wrong way around. Make sure the paper comes from the bottom of the roll when it is sitting in the printer. This means the shiny side should be facing you as the paper feeds out.
Hope this helps. Let me know if you are still stuck.
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If anyone needs a Geller / Towa AX-100 cash register manual, c-tech has one here:
http://the-checkout-tech.com/manuals/cashregisters/Towa_AX-100_operating_programming_manual.html
Registerman, October 2010