Don't be silly,
I'm not hitting rocks with blades.... Partially exposed rock can easily bend the mulch cover, as you ride past it....... but hitting the mower shield itself with partially submerged rock... Then it doesn't bend...
If the Mulch Cover contained metal as strong as the Mower Shield.... We wouldn't be having this conversation....
I didn't make the mulch cover, Exmark did.... I'm just trying to co-exist with a problem.... and come up with a decent solution!!!
I've posted multiple other issues here that remain un-solved.... Like....
Manual with errors in it that Exmark Support has no reference on... No Updated manual available...
Troubleshooting issues that are not listed in the manual....
Wanting to add a hold down system to attach a weed-eater....
Trying to find a decent sized water bottle that will actually FIT the water bottle indentation in the Quest S.....
And nothing ever gets posted.... !!!!! Kind-of Negates the usefulness of a forum if no one actually assists one another!!!!

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People are all different.
Read your posts on the manual and took them as an information post , uploaded for the benefit of other owners, and not requiring any feedback, although we should have posted a thank you or two for which I do appologise.
I for one read every post but if it is something I can not offer any help on I just skim through then close the tab. However you did not have any problems that I could help with so there was no point in me making a response .
Liquise with this post, prior to your addition I have nothing to offer the OP and have only chimed in to refute you claim that no one helps one another.
Exmark are a small company with a very small market share so Exmark specific posts will not get a big response on a purely mathematical basis.
There are a lot forums full of posters who post dozens of times a day on everything but say nothing of any use.
This forum OTOH seems to attract people who only post if they have something they consider useful to the OP and that makes it very concise and easy to search for answers which a lot of people do rather than start a new post.
I don't own an Exmark so I can not offer any help with water bottles or mounting a line trimmer, in fact I missed your request for that information, so here is the best I can do for you.
1) mulch plug- Exmark problem either make one out of old tyre that will bend or get a heavy one welded to the deck or go shopping and find one that can be made to fit. The Great Dane ones are the same heavy steel as the deck, all that I know.
2) manual - Exmark problem, nothing that I or any one else can do to fix that
3) Trimmer- don't know the layout of your mower but my customers fitted a U bracket to the ROPS and another one to the frame so the trimmer points down.
They all use a bent shaft trimmer cause you can not get the trimmer head on a strait shaft low enough to trim with while sitting in the seat.
A lot more have fitted a shelf over the top of the engine for a tank of weed spray and I have done this modification for several customers.
4) water bottle, go to a push bike shop & buy a clip on one with some brackets