What happened to it Mike.... I forgot to follow it?

Centrifugal forces are  a nonlinear,function ie, if you double the RPM, you quad triple the force. Therefore the weights will  require heavying , then the spring tension will adequately deal to the rest.
There are calculators on the web to deal with this, type in your existing weights and RPM you have now, then find the weights to give the same force at the new lower  RPMs.
Here is one

http://keisan.casio.com/exec/system/1271292951

Glort, that one is a hard case. Massively overgeared, im picking around a 9:1 speedup making the little 3.5 even more hopeless to run the 5kVa alternator. This simply cannot work efficiently in that configuration.  Markons are great alternators.

I would doubt a serious New Zealand buyer would  consider that on both price and freight cost, when similar can be had locally for around $NZ500, these genuine Listers are far more prevalent here and come up on our auction sites frequently. The Kiwi  slang for these time wasters is "tyre kicking".
In saying that, bugger all at present, a couple of old petrol engines though, and a 3 cylinder diesel at probably a good price...
https://www.trademe.co.nz/Browse/SearchResults.aspx?searchString=lister+engine&type=Search&searchType=all&user_region=100&user_district=0&generalSearch_keypresses=6&generalSearch_suggested=13&generalSearch_suggestedCategory=

My Lister has not run for months, the solar panels daily are giving 30 amps for around 5 hours, obviously tapering off morning and evening as the sun moves around. Given the capacity of my battery bank, thats as much as I can store, in fact most is now being wasted. I may change to a 48 volt system next year if this global warming thing takes off, its improved our weather enormously, thanks to all the high emission Lister owners. There is something hugely satisfying making and consuming ones own power.

I think  this revolves around the poor sods that live in a built up area as opposed to us lucky ones who live in the sticks. Here we can throw a coil of alkathene on the roof, take 10 minutes with a few Hanson fittings and have a hot shower shortly after.
The "city" dwellers have things like neighburs and councils and need to be socially acceptable, and cant have any exposed  outdoor shower or running around wet and naked. How to explain that when the police are called by that snowflaker next door.
They need to have a private cubical, a tidy solar heater on the roof, and spend far more time and money to satisfy the status quo, of what is considered acceptable behaviour in suburbia.
Good one Mike, thats a method been used down here since alkathene pipe was invented.
We also learned to toot the car horn first  when  visiting unexpectedly.... likely an outside shower, naked sunbathing or toilet may be in use.....
Redneck etiquette.

We call these things a caliphont here in NZ, and can highly recommend them. Mine is a "Rinnai" brand, it uses 2 D cells to run the igniter, these last around 5 years.. Despite its cheap appearance, it has served me with no issues at all for 17 years. It has many  safety features,  a 20 minute timer that limits the time it can run.... in case a pipe bursts etc. It will shut down if water pressure drops, and requires a minimum flow rate of 2 liters a minute. This runs my shower, and kitchen tap.. I use around 9 kilos of LPG in a 6 week period, showers every night. One nice feature is the instant hot water when the tap is turned on.... no waiting cause they can be mounted close to the tap.  Also saves money on not needing a shower mixer, the water temperature is adjusted  on the caliphont instead, and will hold its setting very accurately over time. The flow rate can also be adjusted with a second knob.
Rain water is fine for these, after all, rain is distilled water and has no added "goodness" unless you live in a some polluted place.