coil noise when bumped on 4000

Hi all ,nipper here, this is my first post on this forum so firstly thanks for all the invaluable info you guys freely give to one an all on this site! . I get out for a pan now and then and use a small highbanker I built which I love using, also swinging an old xt17000 around wildly with no great return! despite a couple years pretty intensive research around my closest goldfields. but i've learn't a lot and any excuse to get out in the bush is a good'n .
Anyhoo I decided to do a day course with the 5000 to get up to speed a little ,then hire a 4000 from a local guy and go to some of the areas I had no luck with the xt. Did some research on here and found the "Suggested custom mode settings " on one of the threads, decided to go with the "Patch" settings. the 4000 had a mono eliptical abt 12x8 ? ish and after testing on a 1 grammer I was happy with the response, But I found as I was moving about EVERY time the coil was bumped into twigs or rocks lightly it would give a squeel similar to a small shallow target ,this made it hard to concentrate on the fainter signals , So my question is how normal is this and should I have turned the sensitivity back? I checked all leads etc. just seemed to be when bumping the coil itself. any thoughts would be great as I'd like to take it out again a few times before commiting to an upgrade.
cheers , nipper

Hi Nipper

Would that coil be a "coiltek 12x8 Mono Platypus" ???
solid resin filled coil..

If thats the case they are a bit prone to touch sens, you would be better off just running the front panel as
Deep
Sens/extra
Fixed
DD

Gain at 10

The patch mode on the 4000 is to bloody twitchy for my liking.


Pete in WA

Thanks for the reply Beepinpete, the coil was an open type (spider?) and the labels were so worn that I couldn't read size or type ,this thing probably gets a flogging on wknds and maybe little service as the detectors are a side line from the main business , but they're close handy. I was able to get the threshold good just was'nt sure if it had a fault that might need looking at. They have a 5000 also but she's $120 per day ,sort of puts the pressure on from the get go at that money.
cheers ,nipper