I recall having to do something similar after a drive-train overhaul- anything more than a gentle nipping-up of the drive-to-chassis securing nuts obviously distorted things too much, at least it's secure to the capacitor frame itself! RCA obviously knew that things were a bit flimsy and prone to distortion here, hence the riveted piece of angle along the fly-wheel slot in the chassis. The drive-train is a bit of a weak-spot generally with its (albeit split) "alarm clock" wheels and lack of end-stop mechanism (other than the VC gang itself
). The Scott RCH gear-train currently on the bench here is about three times the mass of the AR88's, with much thicker, precisely machined split wheels and geared end-stop dowels. It's also floated from chassis in both horizontal and vertical planes on springs- possibly a stipulation in a maritime receiver subject to heavy seas and/or blast. Even the supposedly lowly CR100 has much sturdier framing, compact layout and end-stop provision. I think the AR88's design budget was under pressure at drive-train stage....