Hoping someone here on CN has this Giro mount and can help me with a question. I think, but am not certain, this was called the Giro Mini-DX or a similar name. I purchased it maybe half a dozen years ago to use with my AstroTrac, to balance out telephoto lenses and small scopes. The last time I used it was for viewing the last total solar eclipse here in North America, and I did not notice anything unusual about it back then. It has been sitting unused in a closet since then.
Last week, when I got it out and loosed the azimuth lock (the lever on the base with the red button), the bottom plate separated from the alt-az head when I lifted the assembly up. Once the azimuth lever was loosened totally, nothing held the bottom base plate on. It is possible this is the way it was designed, and I either always had the azimuth lock tightened or had the head mounted onto a tracker or tripod for use, and so never before noticed this aspect of the design. But it seems odd.
The second photo shows this baseplate removed with the bearing surfaces both facing up. There is a plastic washer with some light grease to smooth out the azimuth motion. The central azimuth axis is a smooth cylinder with no ridge that would keep the assembly together when the azimuth lock is released. The three holes on the bearing surface of the bottom plate penetrate all the way through to the bottom surface of that plate, and are not threaded. So I don't think these three holes were intended to somehow secure the bottom plate to the rest of the alt-az head.
The third photo shows the bottom side of the base plate (i.e., the surface that would connect to the tripod screw). The central hole is threaded to accept a 3/8-inch tripod screw. The three small outer holes are unthreaded. On the same shelf where I had this stored, I noticed this small brass cylinder or pin, approx 4x4mm in size. However, it is not a press fit into any of these three outer-rim holes; possible it could be hammered in, but that seems a strange way to assemble this head. And I only found this one brass pin, not three. This pin also does not fit into the hole in the plastic washer that forms the bearing surface (and would serve no obvious purpose there). It is possible this brass pin came from something else in the closet and is unrelated to this Giro head.
So what am I missing here? Seems odd the bottom plate of the alt-az head is totally unsecured to the rest of the head when the azimuth lock is released, but it is possible I just never loosened that lock enough to notice this. I appreciate any insight that a current or former owner of this head can offer. Thank you.