2.5na cam / tappet issue

Hi Guys, new to the forum, have read it many times and always got the answers i needed, now my turn to pose a head scratcher (or possibly just show my ignorance!) please excuse if the latter is applicable.

So.. went to the north during the week, purchased an '86 2.5 na 90 (14j). She is a beaut, so original and sound also. Anyway, 2 days of driving it around i was sure there was a tapping noise that was getting worse. Always a worry if just being too paranoid about new vehicle noises!

Removed the rocker cover just now and the rocker closest to the rad was slack on top of the valve by about 5mm or more. The others were fine. Managed to get the push rod out which wasn't bent, but when in position it was lower than the others, so i can only assume the tappet assembly is at fault. Spoke to brother in law who is REME and he said the tappets sometimes break up.

So my question is; whats my quickest and easiest way to sort the problem. Am i right in assuming its a head off job?

(Second Land Rover i have purchased which has needed a rebuild within 2 weeks of ownership! 1st was a disco to be fair!)

Any advice / help gratefully appreciated.

Have you tried adjusting the tappet, irrespective of the length of the push rod, and if so did it sort out your problem?

Do you have much more play on that rocker compared to the others?

It could be that a previous owner has gone and stuck an oddball push rod in ... these things have been known to happen!

Thats true, i didn't take another pushrod out and compare. To put it into perspective i could have adjusted the rocker to the necessary gap but the adjuster has no threads left protruding the rocker to be locked off with the nut.

Does anyone know the stock length of a 2.5 NA pushrod?

The engine (a 14j) has, seemingly, recently been rebuilt and the tappet locating bolt for the 1st one (the one in doubt) is a shiny head as opposed to the others which are older. So i'm thinking something don't seam right!

brass follower can easily be damaged if push rods not located in socket properly ,new cheap rollers can wear greatly to change either needs head removing ,brass follower can be seen with torch down push rod hole