I bought the Johnsonian VI from Bintel over 10 years ago. This was the budget model the other being the Johnsonian V. Johnsonian closed down but the same platforms were then sold by JMI as Nightrider I (VI) and Nightrider II (V) with user instructions for both still on JMI web site.
My VI developed a jitter every 10 seconds or so causing the image jitter. I thought it was the electronics or motors or even gears but no. This past weekend I determined the cause and fixed it by simply removing gunk that had deposited itself on the two bearings with a wire brush. Good as new now.
There are plenty of plans on the web if you want to build something yourself. I didn’t and was fortunate that Bintel were selling these when they did. The Johnsonian was at the lower end of the price scale and at the upper end are platforms from; http://www.equatorialplatforms.com/
Very nice though but there are a few other manufacturers that perhaps others can vouch for.
You're welcome. Unfortunately some of the links are old or broken. The EzCBP looks simple but the web site is either down or non-existent. If you search for EzCBP separately plenty of images and reviews and step by step instructions come up. Also search for Poncet platforms as they are also known as this.
I'm sure someone on iceinspace brought this topic up recently but I could not find the thread. I'm also sure someone in the Australian astro community has built an EQ platform or two. Just need for them to tune into this forum.
Hopefully someone else can help you.