New to this forum and as this is my first post, i shall make it a good one...
I play DOND 250 all the time at my local rileys, and have noticed a cycle of about 12 to 15 days for the Superboard Jackpot (250)
I appreciate i have no hard evidence as this has only happend twice to me so far.. but i will explain...
Both times I Jackpotted the crap out of it - it started by flashing £12 nudge or a 4 noel exchange - DO NOT PRESS EXCHANGE OR COLLECT.
LOOK FOR THE REMANING NOEL ON THE REEL and bring it down manually.
For the regular players of this machine, you will often see it spin in a 4 noel board entry like this...

... With the jackpot coming, the Noels drop in differently... (both times the same for me)
NOTE: I have only ever had the jackpot twice - but both have started with the £12 Nudges flashing! No other nudge/4noel exchange has been the jackpot. (The £12 Nudge Drop rarely flashes as it is usually very low numbers to start the money gamble, or if the machine needs to give a quick fix payout - it will offer a nudge drop of £20 which can usually be gambled up to £30, on a 2 then HIGHER or 11 then LOWER.
My quick tip firstly would be to not constantly press spin.. as this clubber is rather slow at times and it can take a few seconds for HOLDS or NUDGE / EXCHANGES to kick in.
THIS IS NO PROMISE IT WILL WORK 100% OF THE TIME, it is sum sound knowledge i have built up so far in playing this machine.. so for all those that are interested.... if you spot a £12 nudger exchange kick in - drop the four noels like the pic - you may very well have that jackpot in ur box!
A VERY LONG POST I KNOW, but i hope i have given some of you an insight to this machine...
Replies would be most welcome as this is my first post..
Cheers.
Dave