I did versus similar to you when I came back to fishing after years ‘off’
I ended up the same, my movable ‘tighten & clamp’ seat wasn’t pressed down enough by my 6500CT reel Foot so I ended up making it worse by fitting one of the huge bulky Penn Coastal seats which locked in place with a collar at either end . To be fair it did what it was supposed to well but It made the set up so bulky I could barely get my thumb round the reel spool :Oo:
Tried the Penn Talon , ABU Grip Loks, coasters, in the end I bought a Zippy 4500S from a lad on here and he’d ‘fixed’ his seat ( standard glue on type Fuji) in place solidly but not permanently by doing as you’ve said & packing under the seat with tape til it was a really tight fit and ALMOST unmovable but JUST about movable with perseverance & patience !
I get no movement in it, ever, cast multi pendulum reel down & fixed spool both up & down the butt and just use this set up every time on all my rods that don’t have fixed reel seats.
Sadly not all tailor made clamp down seats work as well with every reel foot as you’d expect but often seating on a bit of tape can help . Coasters are pretty foolproof but many don’t like them as they do tend to carve up reel feet which can be a pain in pretty painted ones
There’s no right & wrong really & no one size fits all , you’ll settle on what suits you best . I’ll get a new rod, take it out & establish where the reel placing works best then lock it down there but movable seats are useful particularly if you cast reel up and fancy a try with it lower down the butt .
If you’ve got a decent shop nearby pop in with the butt section & reel & see what they can show you , chances are with a bit of tweaking the factory one will do the job but it doesn’t hurt to have a look.
We all end up a right bunch of bodgers :laugh: rings held on with tape, rubbing candles on worn spigots , some lads fix FS reels on with wraps of old inner tube .. whatever gets you fishing :thumbsup: