I went through your hubs. Some suggestions in three groups, please don't get offended.
1) (a) write more hubs - you can expect decent traffic only after some 20-30 hubs if everything else is good (b) divide your topics into modules and put good headings to them (c) write with key words and topics that are of general interest (d) optimize your pages so that search engines will understand what your page is about (e) some back linking is needed to get recognized by search engines (e) I don't see adsense on your hubs. Compared to Amazon, adsense is more easy for many.
There are many successful people on hub pages who have written how to earn money with hub pages. Make a search and read more. Search the hub pages forum also, where lot of such good information is there.
2) Were you getting income earlier and now dropped? For many established hubs this happened in recent months. This is because of Google algorithm changes. If this is so, keep working on in the right direction and things will come up (but this may not be the case for you).
3) Most important point: When I searched Google for your hubs (site:your hubname), i just saw only one out of six. This is quite serious. This means that either your hubs were never indexed or if they were indexed, they were de-indexed. You need to do some investigation on this and act accordingly.
Hope these pointers are helpful. Keeping reading, writing and continue your efforts. All the best.