Don
I would make sure everything is flat and clean. Then glue
the gaskets to the valve covers with spray adhesive.  Then I use a thin smear of grease on the other side of gasket that
seals to the head. The gaskets last a very long time this way. 
You may need new bails and covers if they lost tension/bent. 
Busdepot used to have some OEM covers. I know GoWesty 
sells a kit that uses all repro parts. I have no experience with 
GoWestys kit just seen it advertised. 

Bill M
Mystic,CT
Go Sandy!Go!

On Oct 26, 2012, at 7:24 PM, Don Preston <dj@FOKUST.COM> wrote:

> Hi all,
> 
> So, while replacing the exhaust system a couple weeks ago I also replaced the rocker covers, with new cork seals, as one of them was leaking. Thing is, now both covers have slow leaks, yay!
> 
> Anyone run into this? Tried bending clips to get as tight a seal as I could, and made sure the seals are contacting properly. Ideas?
> 
> Don
> '87 2.1 Vanagon GL ASI